I walked into the state farm agency and told them I was going to buy a school bus and eventually turn it into a camper and asked what they could do for me for insurance.
They said I could get a commercial policy for a bus.
once I purchased the bus I brought it home, Every new purchase has a grace period of 30 days where you are covered under an existing policy, so I was able to bring it home with no worry.
Once all of the seats, flashing lights, school bus letters, stop arm and the passenger capacity number by the door removed, and I put stick on letters saing this was private rv I called them back, told them I had my bus and what i had done. By removing the seats and the capacity number on the out side I now had a non commercial vehicle, and they issued me insurance for a bus. They requested pictures of the inside and the outside so I sent them tons of pictures.
insurance is all about limiting the liability to their pocket book, go with what ever they will give you insurance for. I did not do full coverage.
As this bus sits it is a private bus, I can use it for what ever I want as long as it is not for commercial use or transporting more than 16 or so people.
Do not try and deceive the insurance company in any way, if you swap a vin and have an accident they will verify the vin number on the frame or on some other panel that you did not change, then you have committed a felony, you are not insured and your life will be a big mess.
A friend of mine had a bus and his insurance asked him what he was going to do with it, he had planed on using it to transport water in a tank to catel out in a field, they insured him as a private truck.
The commercial conversion job that is easy to get insured as an rv is because these companies follow all of the electrical codes, and structural changes are stamped by a professorial engineer, this limits the insurances risk.
A private conversion they have no way to know if you wired your electrical correctly and some one gets electrocuted, they will pay.
Good luck.
~C