Why not let the Chevy dealer find the problem (especially if the vehicle is still under warranty) and if they want to charge you, call the RV dealer and tell them the bill is going to them?
If they refuse, you will least know that the RV dealer is disreputable, and taking him to small claims court will soon change his attitude—and cost you nothing.
I have not seen any bolts - were these left off or did they come off afterwards?
The bolts must have been removed to retrofit the RV to the cab & chassis and MAY have not been reinstalled. This is why the Ford dealer wants to look at the Plus again . . . and if they charge me, the bill is going to the RV dealer and, I assume back to Trail-Lite/R-Vision.