Finding RV insurance that allows short-term rental (AirBnB)

Check with a smaller, local insurance agent. Explain to them exactly what you're doing and see if they have a smaller insurance company that understands what you're trying to do. It may be as simple as a rider on your homeowners.

A few years back we were doing a TT rental, it worked great.

On our last trip to Arizona we rented a 5th wheel as a ABnB, it was functional. Fortunately I was handy with RVs as I ended up fixing a few issues. The host was good and did give us a partial refund for me work too. :B