According to the V12 Help, "If -c is used, dbtran attempts to translate the online transaction log file, and all the offline transaction log files in the same directory as the online transaction log file." so if your 8,000 offline logs are in the same folder as the active log, you should be able simply do this:

"%SQLANY12%\bin32\dbtran.exe"^
  -c "ENG=inventory; DBN=inventory; UID=dba; PWD=sql;"^
  dbtran_inventory_sql_1.sql

PAUSE

This works OK when you run it on the computer where the log files are located. In this test, there were two offline logs AA and BB, plus the active log, all located in the same directory.

The displayed output is hugely confusing...

C:\projects\foxhound_benchmark_inventory_db>"C:\Program Files\SQL Anywhere 12\bi
n32\dbtran.exe"  -c "ENG=inventory; DBN=inventory; UID=dba; PWD=sql;"  dbtran_in
ventory_sql_1.sql
SQL Anywhere Log Translation Utility Version 12.0.1.3797
Processing transaction logs from directory "C:\projects\foxhound_benchmark_inven
tory_db\"
Transaction log "C:\projects\foxhound_benchmark_inventory_db\140221AA.LOG" start
s at offset 045301888397
Processing transactions from transaction log "C:\projects\foxhound_benchmark_inv
entory_db\140221AA.LOG"
 46% complete
Transaction log ends at offset 045301892717
Transaction log "C:\projects\foxhound_benchmark_inventory_db\140221AB.LOG" start
s at offset 045301892717
Processing transactions from transaction log "C:\projects\foxhound_benchmark_inv
entory_db\140221AB.LOG"
 96% complete
Transaction log ends at offset 045301896991
Processing transactions from active transaction log
 100% complete
C:\projects\foxhound_benchmark_inventory_db>PAUSE
Press any key to continue . . .

But the output *.SQL file contains the correct transactions; in this test, there were two offline logs, each with a single UPDATE SET item_count = 111 and 222, plus the active log with a single UPDATE SET item_count = 333:

--CONNECT-1006-045301892518-DBA-2014-02-21 08:04
--BEGIN TRANSACTION-1006-045301892529
BEGIN TRANSACTION
go
--UPDATE-1006-045301892617
UPDATE DBA.inventory
   SET item_count=111
 WHERE item_id=1
go
--COMMIT-1006-045301892634
COMMIT WORK
go
--CHECKPOINT-0000-045301892648-2014-02-21 08:04
--CHECKPOINT-0000-045301892694-2014-02-21 08:05
--CONNECT-1006-045301896838-DBA-2014-02-21 08:06
--BEGIN TRANSACTION-1006-045301896849
BEGIN TRANSACTION
go
--UPDATE-1006-045301896937
UPDATE DBA.inventory
   SET item_count=222
 WHERE item_id=1
go
--COMMIT-1006-045301896954
COMMIT WORK
go
--CHECKPOINT-0000-045301896968-2014-02-21 08:06
--CONNECT-1006-045301901112-DBA-2014-02-21 08:08
--BEGIN TRANSACTION-1006-045301901123
BEGIN TRANSACTION
go
--UPDATE-1006-045301901211
UPDATE DBA.inventory
   SET item_count=333
 WHERE item_id=1
go
--COMMIT-1006-045301901228
COMMIT WORK
go
--START CHECKPOINT-0000-045301901231-2014-02-21 08:26
--FINISH CHECKPOINT-0000-045301901252-2014-02-21 08:26

(it would be nice if the output named each log file, wouldn't it?)

Alas, that technique does not seem to work for a folder located on a different computer:

"%SQLANY12%\bin32\dbtran.exe"^
  -c "ENG=inventory; DBN=inventory; UID=dba; PWD=sql; LINKS=TCPIP(HOST=dgrk3x31;DOBROADCAST=NO)"^
  dbtran_inventory_sql_1.sql

PAUSE

The displayed output doesn't explicitly name the offline logs, and it appears that dbtran is looking for "C:\projects\foxhound_benchmark_inventory_db\" on the local computer where it does not exist, rather than the computer where the logs are located (that's not a user error, nowhere in the dbtran command is the folder specified):

C:\projects\$SA_templates\run\dbtran>"C:\Program Files\SQL Anywhere 12\bin32\dbt
ran.exe"  -c "ENG=inventory; DBN=inventory; UID=dba; PWD=sql; LINKS=TCPIP(HOST=d
grk3x31;DOBROADCAST=NO)"  dbtran_inventory_sql_1.sql
SQL Anywhere Log Translation Utility Version 12.0.1.3298
Processing transaction logs from directory "C:\projects\foxhound_benchmark_inven
tory_db\"
Processing transactions from active transaction log
 100% complete
C:\projects\$SA_templates\run\dbtran>PAUSE
Press any key to continue . . .

The output *.SQL file only contains the UPDATE from the active log...

--CONNECT-1006-045301901112-DBA-2014-02-21 08:08
--BEGIN TRANSACTION-1006-045301901123
BEGIN TRANSACTION
go
--UPDATE-1006-045301901211
UPDATE DBA.inventory
   SET item_count=333
 WHERE item_id=1
go
--COMMIT-1006-045301901228
COMMIT WORK
go

In your case, it may be a moot point. I suspect your 8,000 offline logs are located in a different folder from the active log, so you will need to use dbtran -m.

Here is a test where the offline logs were moved to the "bkup" subfolder under the folder where the active database and transaction logs are located. Like the second example above, dbtran is run on a workstation computer different from the server computer.

With this syntax, the -c must be removed and -n must be appended in front of the output *.sql file name:

"%SQLANY12%\bin32\dbtran.exe"^
  -m "\\dgrk3x31\c\\projects\foxhound_benchmark_inventory_db\bkup"^
  -n dbtran_inventory_sql_2.sql

PAUSE

C:\projects\$SA_templates\run\dbtran>"C:\Program Files\SQL Anywhere 12\bin32\dbt
ran.exe"  -m "\\dgrk3x31\c\\projects\foxhound_benchmark_inventory_db\bkup"  -n d
btran_inventory_sql_2.sql
SQL Anywhere Log Translation Utility Version 12.0.1.3298
Processing transaction logs from directory "\\dgrk3x31\c\\projects\foxhound_benc
hmark_inventory_db\bkup"
Transaction log "\\dgrk3x31\c\\projects\foxhound_benchmark_inventory_db\bkup\140
221AB.LOG" starts at offset 045301892717
Transaction log "\\dgrk3x31\c\\projects\foxhound_benchmark_inventory_db\bkup\140
221AA.LOG" starts at offset 045301888397
Transaction log "\\dgrk3x31\c\\projects\foxhound_benchmark_inventory_db\bkup\140
221AA.LOG" starts at offset 045301888397
Processing transactions from transaction log "\\dgrk3x31\c\\projects\foxhound_be
nchmark_inventory_db\bkup\140221AA.LOG"
 91% complete
Transaction log ends at offset 045301892717
Transaction log "\\dgrk3x31\c\\projects\foxhound_benchmark_inventory_db\bkup\140
221AB.LOG" starts at offset 045301892717
Processing transactions from transaction log "\\dgrk3x31\c\\projects\foxhound_be
nchmark_inventory_db\bkup\140221AB.LOG"
 99% complete
Transaction log ends at offset 045301896991

C:\projects\$SA_templates\run\dbtran>PAUSE
Press any key to continue . . .

Now the output *.sql file contains the transactions from both offline logs (but not, of course, the active log)...

--CONNECT-1006-045301892518-DBA-2014-02-21 08:04
--BEGIN TRANSACTION-1006-045301892529
BEGIN TRANSACTION
go
--UPDATE-1006-045301892617
UPDATE DBA.inventory
   SET item_count=111
 WHERE item_id=1
go
--COMMIT-1006-045301892634
COMMIT WORK
go
--CHECKPOINT-0000-045301892648-2014-02-21 08:04
--CHECKPOINT-0000-045301892694-2014-02-21 08:05
--CONNECT-1006-045301896838-DBA-2014-02-21 08:06
--BEGIN TRANSACTION-1006-045301896849
BEGIN TRANSACTION
go
--UPDATE-1006-045301896937
UPDATE DBA.inventory
   SET item_count=222
 WHERE item_id=1
go
--COMMIT-1006-045301896954
COMMIT WORK
go
--CHECKPOINT-0000-045301896968-2014-02-21 08:06

---

Thank you for asking this question! In my efforts to reproduce your symptom I discovered that a SQL Anywhere 12 database running on an older, rather feeble performance test computer had a 32 GB active log file... no big deal, except when the drive capacity is only 74.4 GB... now it has 32.2 GB free space, which tells you all you need to know about what life was like on that computer... before your question, that is, now life is good:

All Clear - Alert #7: The free disk space on the drive holding the transaction log file has fallen below 1G.
All Clear - Alert #6: The free disk space on the drive holding the temporary file has fallen below 1G. 
All Clear - Alert #5: The free disk space on the drive holding the main database file has fallen below 1G.

Again, thank you!