the insurance company doesnt care about CDL or not.. CDL or not is a state's issue.. i cannot speak for virginia as far as vehicle registration and licensing... but the insiurance company strictly looks at the vehicle and the risk they take..
progressive and many other insurance companies feel thast converted school busses are a bad risk... most of the people on this forum are careful about securing their installations, balancing loads, center of gravity, front to back weight distribution, etc..
HOWEVER there are a LOT of poorly converted school busses out there where a quick stop will send a frig or a table flying right into the driver compartment.. or a heavy side loaded conversion that will flip easily etc... they found that there was likely too many claims...
some insurance companies wont insure custom cars either.. mainly because of the liability portion.. when you carry 100/300 (standard). most often even in a major claim.. they dont pay out near that amount of money for the medical liability or property repair....
if you dump a school bus theres a lot more hurt than can be inflicted on people..
obviously its entirely possible to dump a commercially made RV as well.. I see them smashed to pieces all the time on my florida trips from ohio... but the RV makers have to pay attention to balancing, loading, etc ...
again the arguments dont make a ton of sense as school busses are heavier duty, safer, etc.. but they go by how much they pay out on average.. so at some point they mustve paid out a lot on converted school busses as a whole in the insurance industry..