"Avoid anything smaller than a 300watt, and avoid 2x10 or other small rigs for weight, you don't play bass so you can drag around a lightweight rig, it's not conducive to good bass reproduction anyway, also avoid the cheap stuff, distortion hides bad guitar tone many times, but bass is intended to be clean, and cheap under powered rigs will distort, and sound like bunk."
GO for 4x10 AND 1x15 cabs, and consider at a small venue if you want to leave the 1x15 in the van. (I'd always use it.) Don't ask the sound guy to put some bass in the fold back as with most small pas, that's going to mess it up for everyone else (even if he agrees to do it). And totally forget relying a bass wedge - as one bass guitarist insisted he do at an audition with me. (He didn't get the job). Separate heads are vital for carrying... the more powerful the better.