Try Progressive Direct !! they are different than your local progressive agent.
A few years ago (maybe 4??), I had liability only on my bus with Nationwide. NC, in it's infinite "we not only tax everything, we 'regulate' the h**l out of it" wisdom, set some stupid thing that caused Nationwide to drop either bus conversions or motorhomes (don't remember exactly what the letter said) -- of course, they would be happy to continue to take my money for car insurance but they were dropping the bus. I went to Progressive, spent 45 minutes on the phone with them, and after answering every question in the world short of how tall my daughter's dog is and a few "I need to speak to my supervisor, can you hold?" delays, they said "we have decided not to offer you coverage". I dunno if it was the NC thing or is my bus is "too unconventional" but Progressive turned me (one accident in 30 years and that was *being hit by a drunk running from the cops not my fault*) down flat.
Just my experience. BH NC USA