Jeez, it looks like storing the car inside a school bus takes up more room than I was originally thinking. You'd lose all but the first three or four rows of seats. Still, we could have fold-up bunks in the car area like Tetanus does in their box trailer. That would leave us something like 7' x 7' to fit road seating for 5, a kegerator, and storage for the toolbox, large totes, and other stuff that won't fit in the Dart. That sounds doable. Still, it's a lot of fucking work and added expense, which offsets the initially low purchase price. And whenever we wanted a car trailer for a Random Stupid Thing, we'd have to break out the party bus, which wouldn't be terribly convenient.
The smaller city-type buses would be nicer in many ways- actual adult standing headroom, less work to furnish. They'd probably be geared for city driving, but that being said, compared to the purchase price, a rear end gear swap isn't that expensive. It would require a separate trailer, but used flatbed trailers aren't THAT expensive. I doubt a diesel-powered brick would feel much difference in MPG towing vs. not towing. It would be more convenient to have a separate trailer if we needed it.
So there are basically three options as I see it:
1. School bus, onboard hauling
-Least money
-Most work
-Lowest flexibility for bus layout, meaning less fun on road trips
2. School bus, towing flatbed
-More money: add trailer + tow hitch to #1
-Less work, at least up front
-More flexibility for future layout, meaning more fun taking it on road trips and such
-More flexibility with respect to non-LeMons car towing (Bob's single-cab truck can pull a flatbed if you're gentle)
3. Transit-type bus, towing flatbed
-Most money: add higher purchase price and a gear swap to #2
-Least work, at least up front
-Similar layout flexibility to #2, trading off floor space for overall quality and headroom
-Same flexibility w.r.t. non-LeMons towing as #2