I agree with Rick about keeping amps and drum kit close together. I have done it this way, with guitar amps literally right beside the drum kit facing the same way the drummer is facing, and it worked well. We used small amps, may not work so well with a dimed Plexi or whatever.
I would, however, suggest that you should at least be prepared to DI or isolate the bass. The bass amp will be in everything (due to the nature of sound at low frequency) by the time it is loud enough to be heard. You could filter it out, but there will be a price for doing so.
I would also say that the smaller the room, the more dead it will need to be not to be a total mess. When I did this, I used a widely (as wide as the room) spaced pair of LDCs (414s) to get a blend-able room sound, instead of trying to get room sound out of the close mics in a relatively dead room.
Take your time setting up, check mics in pairs (in mono) for phase issues...