Depends on your insurance company but in some cases at least they don't care what your or your states definition of an RV is. They won't even care what it's registered as. They run the vin and whatever that began life as is what it is, as far as they're concerned. If you have it "converted" by someone like Sportsmobile (just an example), or somebody that is a certified or registered RV converter, it can be a different story. What constitutes an acceptable conversion company I have no clue, and like all the above, is probably insurance company dependent.
I tried a handful of different providers and ended up with Progressive. I still had to get commercial coverage, but cost wise the difference was negligible. The funny thing was, most of them wouldn't cover it period because it was a "commercial" vehicle that had been partially converted to a camper, and since neither I nor the PO were certified converters they wouldn't touch it. Progressives commercial provider just wanted to hear me say I had removed any RV stuff, and I was good to go. Whatever I did with it after was ok as long as I didn't say RV. Overnight job site command center? No problem. Mobile office with convenience package? Not a big deal. Just not "RV". Semantics.