I'd first report the burned wiring harness to Keystone and to the dealership. I wouldn't drag the trailer to the dealer, at least not now, but email them the photos and a description of what happened. It may or may not be something that Keystone is already aware of, but that has not yet risen to the level of a recall or a field replacement. Your incident may (or may not) be the one that triggers a recall.
Additionally, I'd recommend you fill out a complaint form at NHTSA:
https://www.nhtsa.gov/report-a-safety-problem#index
While none of the above actions will "get a replacement wiring harness delivered to your door with a voucher to hire a repairman" it may get the ball rolling toward getting the system on the "problem watch list" or even initiate a recall....
After all, the recent propane regulator replacement program didn't get started by people "ignoring a leaking regulator" but by people "identifying the problem to Keystone and NHTSA. This may go the same route....
As stated, the Keystone factory and as far as I know, no dealerships monitor this privately owned website forum, so there's no mechanism on this forum to notify anyone at a dealership, the factory or the state/federal government agencies of a problem from here.