Actaully a bus is heaver than the same size motorhome body, its all the inside gear which makes the motorhome heavy. Motorhome bodies are usually made from thin wood cvered in thin sheets of aluminum while a bus is made of solid steel. If you have ever seen either in a wreck, a motorhome withn explode into toothpicks and a bus will dent up a little and keep on going. Buses are heavy even before you load them with gear.

Traction: Dual wheels are there to spread the weight across two tires instead of one. Once your off pavement or in snow/mud/whatever on top of the pavement this wonrk against you because you want to sink in through whatever is on top of the pavement or sink in enough to get a bite. Dual wheels tend to float higher than a single wheel. Also dual wheels tend to get crap stuck between them. Look at any of the off road forums, or other off road vehicles like earthroamer, they swap dual for single wheels. We have pulled plenty of school buses out of snow with our old Massey Ferguson tractor.

as far as the decidated vehicle, I was making the point that with a better vehicle then you could have it either dedicated or drive it to work, with a bus you really can't drive it to work.
Most pickups today are extended or 4 door cabs so you can haul the family with you and still have room in the back to sleep. Then if you want you can either carry a truck camper or pull a camper trailer and get the same advantages as a motorhome with out the disadvantages.

Even if you don't dedicate that bus and use it on the weekends your still getting hit in the wallett. You have to pay for license, taxes, and insurance on it. You have to maintenance it, oil changes, tires, batteries, etc. vehicles which only get driven once a week start to have problems after a while. You battery doesn't last as long, the fluids absorb moisture and need changed sooner, the metal parts rust faster.

I looked at this route a couple years ago, we had the 30mpg car and a 4x4 truck sitting at home. then the airplanes flew into buildings in NY and my wife's work was evacuated since it was a tall building. We had what little bit we could fit in the car and I had to take a couple detours to get it into downtown to get her. My rusty old BOV was sitting safely at home and I could have used it a couple times to jump a curb the car couldn't. Lucky for us nothing major happened that day outside of the 4 planes but if somehting would have happened in out city then we might not have made it home to get our supplies.
I went more middle road this time, instaed of a 5mpg military truck or bus or RV rusting away at home and a tiny econocoffin to go to work I went for a 20mpg 4x4 extended cab truck. I can carry my whole family and them some in the cab along with all kinds of gear. Then I can toss more gear that is prestaged in the garage in the back and sleep in my camper on the back if needed. So I'm always partially ready for anything and I save $ on insurance and don't have to maintain and extra vehicle.
If your wanting something more like a bus then look at one of the class B motorhomes from a company like roadtrek. Then take a full size van which you see the van front in that picture of the small bus) and build an RV body on it instead of a bus body. You can get them empty or order them to your spec. There are retired people who live full time in those.