Man, make my day! Its like a have a bunch of dads on TB!
I would go with another 210, but it feels like that wouldnt be enough power. IT would work much better for me, space wise in my Mazda 3, but Im afraid I wouldnt have the power needed.
I plan to get a Sansamp DI soon though.. so that may solve the problem.
Remember, you will probably only need a rig big enough for you to hear yourself on stage. The crowd will more than likely be hearing what the sound man is mixing. A lot of these huge rigs you see in arenas and big amphitheaters are just for show. I honestly believe that you will have enough headroom with an Avatar 210 and a B212, both at 8 ohms, so your head will put out at full strength. Monitors, whether in ears or floor, will also allow you to hear yourself. Avatars are great cabs for the money and we live in a day where big cabs just aren't needed as much anymore (thank God).