When dealers tell me they don't work on motorhomes for chassis work, I bark back and state it's a Chevy (or Ford) van - the chassis is the same on the MH. They always roll over and say ok, and then do the work.
When we took our Ford into the nearest dealer for brake work when the front rotors seized, they said they didn't work on motorhomes. After trying the van explanation and still getting resistance, I retorted that I'd go to the CHEVY dealer a few blocks away, and that they'd most likely help me. The service writer changed his tune and they did the work with floor jacks just outside the service bay.
When I had a couple of chassis recalls on our Chevy 4500, I got the same pushback. After explaining that it's the same chassis as a VAN, they fulfilled the recalls. Now I get regular service notices on my Chevy Cutaway!
You gotta push them, with statements they understand. IGNORE the motorhome part, FIX your chassis!
