Probably the patch you're using isn't compatible with the bosses and because of that, it won't load correctly and then the ROM freezes.
Also, be careful about freespace, this could be the problem, the freespace you're using are corrupting important data and this could be the reason of the crash.
I'm working on Super FX Development Kit
Yes, Super FX can have 8MB ROMs.
I don't do ASM requests. Be aware of that.