My dealer is out of business having sold out to Camping World 6 months after I purchased the unit.
I think when business A buys business B, they not only take over the assets, but also the liabilities. For example, if the selling dealer had 20 trailers on site, the buyer would own both the trailers (assets), and any money the dealership owed manufacturers for those trailers (liabilities).
If this was caused by a dealer error, standing behind their work would be a liability taken over by Camping World. For example, if Joe Blow had some work done on Monday, and the sale happened Tuesday, and Joe came back on Wednesday with a problem caused by the service, I doubt anyone would argue that Camping World didn't have an obligation to fix the work done by the dealership on Monday.
Your situation is more difficult only because 1) there's more elapsed time, and 2) the cost of the fix might be significant. Nevertheless, the underlying principle is the same and a discussion along those lines might be useful. You could start with local management, but I'd guess you'll end up talking to their corporate management.