I swear, this must be one of those great nights...after some google searching and such, I was able to reduce the mingw version of AIMFix down to a 105KB executable and the memory usage is back down about 300K. For anyone else who happens to google this up, what I found was this:

mingw by default includes a pantload of debugging information with the executable, but there's a util that comes with mingw called "strip" so you run strip on the end product of compilation to get a streamlined distribution file. I also ran upx on it as per the upx docs to shrink it down even more.

i586-mingw32msvc-strip --strip-all AIMFix.exe
upx --best --crp-ms=999999 --nrv2b AIMFix.exe

are the commands I ran, just in case that helps anyone else who runs across this. The advice I found said run "--strip-unneeded" but AIMFix seemed to run properly even with "strip-all" and it saved another 10KB so I am using that for now. If any problems arise I'll try stripping only unneeded.

Finally, I can work on AIMFix without needing Windows to do it!

-Jay