Yet again, after lots of Googling, I found my own answer. Again, in case this is helpful to anyone..

I found the answer here if anyone's interested.

More specifically, if you don't feel like reading, in /usr/X11R6/lib/X11/fonts/misc, there is a file called fonts.alias. The first line is..

Code:
fixed       -misc-fixed-medium-r-semicondensed--13-120-75-75-c-60-iso8859-1
There's the "default font 'fixed'" that I kept getting errors on. If you change the line to..

Code:
fixed       -misc-fixed-medium-r-normal--7-70-75-75-c-50-iso8859-1
..remaster, and test again, X starts up without a problem, and that's with ONLY xfonts-base and xfonts-75dpi installed.

(Actually, I only swapped the "semicondensed" with "normal", and that worked as well - I didn't change anything else in the line).

I'll probably end up removing the 75dpi fonts later on, as I have more programs to look at removing first. So far I'm down to 119 MB compressed. Only 70 MB more to cut down before it will fit on a business card CD-R. Rock.