I came to suggest calling the boat dealers too, glad other already said it. While mine doesn't work on the trailers, they do inspect as part of my spring service. We have a bunch of trailer sales places (not RVs) but only 2 shops that service and they both seem to be of the mindset that they are only going to service as many as they can and they won't be pressured. As mleekamp suggested get to know them and develop a relationship if you can. I tried with one, failed he made it abundantly clear he services what he sells and not the other guys. :(