AFAIK you should be able to have fastmem above that limit located locally to the accelerator with an '030 card. It should autoconfigure at boot-time.
I dimly recall problems with A2000s not reporting the right amount of fastmem but I dunno what the upshot of that is... although I've definitely heard of people using A2000s with more memory than you have.
Someone else will hopefully have more answers for you! :-D
