Dos 8.3 filenames
Is there an option (like there was in Publisher 2003) to produce output files compatible with the DOS 8.3 file naming convention?
No, ePublisher does not have such an option. You can modify the naming convention by performing an override on a file called names.xsl, located by default in the ePublisher Pro installation directory here: ePublisher Pro\Formats\Shared\common\splits\
So, in summary, ePublisher output most likely cannot be configured to produce complete output with valid DOS 8.3 filenames.