Interesting. Never looked closely at a CD32, I had no idea they only had a single ROM chip, but space for a second. Sorry I can't help with your question, but thanks for helping me learn something new! 
Any performance improvement going from 16-bit to 32-bit?
CD32 has a single 16 bit rom, but the schematic shows you how to hook up a second rom so it works in 32bit mode. Apparently in 16bit mode it's not laid out the same as any other Amiga 16bit rom because high and low words are stored separately.
http://eab.abime.net/showthread.php?t=71509The thread appears to show that my idea wouldn't work as it would see the same modules in both.
Probably best way would be to hack together a small boot rom that purely sets up a screen and dumps out hex from various addresses and see if you can get that to run.
