I'm using 20-ton air-over hydraulic jacks from Harbor Freight. These work well for me but are admittedly a bit heavy to sling around too often. The plus side is I can level the bus is about 5 mins after I get them under the bus and can use the air system to do the work.
"You can finally say you have enough horsepower when you leave two black streaks from corner to corner"
(Mark Donohue, famed TransAm driver)