Funny you should mention body heat. I'm from Minnesota and one of the big things they advertised when the Mall of America opened was how energy efficient it was (in the winter anyway) because it doesn't have any source of central heating. All the heat is generated by the electronic equipment in it and more than anything, the people moving around.
With what you're talking about running in that bus, you're going to need one HECKUVA generator. A big battery bank and a good inverter or two will help, but running an AC off the inverter is tough, as discussed before. My recommendation might be to consider getting an engine driven AC compressor along with a gennerator head or a second alternator. Having it all driven off the engine might sound like you're wasting a lot of fuel (the engine has to be running all the time then obviously), but it would be a lot easier than hauling out a big gennie all the time and a lot more cost effective than getting a built gennie ($$$). You may want to look into reducing the power consumption somehow. Flourescent lights are GREAT. They draw less energy, kick out less heat, and are more resistant to the bouncing a bus does. The only downside might be cost, but they last so much longer so it kind of offsets....
Another option would be to run a swamp coolre if the environment isn't too humid. Even in my humid environment I plan to try and build one. Even on the humid days when Ican't use the evaporative cooling, I will have a central air exchanger. Just keeping the air moving can make a big difference.