More information about what is in your autoexec.bat and config.sys could be important to help trim out use less garbage. Also post the output of mem/c/p.
Can't you use a boot disk? Like suggested, load doskey only when you need it. You complain about memory but waste it. Optical drives aren't needed for the games and that can be cut out or reduced to 1. The mouse driver can also be dropped if it isn't used.
Try getting a hold of the proprietary cd-rom/dvd driver that works with a wide range of devices that I believe Freedos used to recommend on their site (can't seem to find it atm). It is no longer on the manufacture's site (not that I can remember the manufacturer offhand), but you can find it from a driver site. The driver is vide-cdd.sys and some other files. The self extracting exe that contains the driver is called apicd214_doscdromdriver.exe. It uses 5,024 bytes total for however many drives that use it if it is compatible.
If you haven't tried them...
1) Shsucdx is a mscdex (cdrom/dvd controller) replacement that uses 5,808 bytes with one drive and 8,240 bytes with two drives.
2) Cutemouse is a nice mouse driver but didn't work right in the Dark Forces demo when trying to control the character last time I checked(not sure about retail). It uses 3,104 bytes. I can't think of anything else it doesn't work with.
3) FreeCOM is a COMMAND.COM replacement. I'm not sure how this compares in memory usage.
4) Jemm386 is a EMM386 replacement, uses 192 bytes, and is supposed to be faster. It might work better.
5)HimemX is a XMS memory manager that can replace Himem. I'm not sure how this compares in memory usage either.
Privateer has screwed up sfx and speech in dos if you have too much ram so it may not be decently suitable on the machine for normal play.