This whole build machinery is pretty opaque to me, so I'm not sure how to proceed. Surely it must be possible to build the target gcc specifically for 68060?I have no clue about that build machinery either, but maybe you want to check _floatex.S and look for the $_exception_handler calls in it. Perhaps they can be converted to 32-bit PC-relative calls, which will result in R_68K_PLT32 relocations.
I never got to the end of that specific rabbit hole, so whenever I rebuild NetBSD for my m68060 machine, I simply replace libm.so.0.12 with one from an -m68030 build (object dir/lib/libm/libm.so.0.12), then resume with -u.
The performance difference between non-m68060 and -m68060 compiled is noticeable.
John