Hello from an old newb from Oregon!
Found your site accidentally. It seems we all have pretty much the same problems with buses and getting them organized for use. I'm working on my fourth or fifth bus ('97 TC1000) and I'm very happy with the extra floor space and completely flat floors.
I've learned you don't mention the words "bus," "school bus," or the all important phrase "non-professional conversion". I register a bus as a van while in DMV, after removing all the seats. You can't change your VIN so insurance companies always see it as a transit bus. The explanation I got about insurability of converted school buses was that most people make their rigs to top heavy and that these have a narrower wheelbase than commercial buses giving them a high rollover risk. It took me a number of days online to find an insurance company that would accept my "Maxivan" and allow me to have decent coverage. I have a nice decent policy with Nationwide.
Nice to find you folks online here. I hope to pick your brains.