Few bother to read their bike rack manual....DO NOT USE ON A TRAILER OR RV.
Very few bike rack OEM's give the OK for trailers and RV's, those that do generally state that its ok, but they will not honor any warranty.
Swagman is one such rack that allows trailer/RV use, and I own two of them. No problems so far, but none of our out of state trips include bikes on the back. They go in the camper for long distance travel.
Front hitches are a great option as well, I used one on our previous TV and had zero issues. There is speculation that these interfere with cooling and whatever...with no facts or actual issues encountered.