I called Jayco about the same thing, I also wanted to hang towel rods on the back wall of our ultralight 221. This was what I was told, If I was to hang anything on the outside walls that weighted over 1 lb. that it could cause the paneling to delaminate and void the Warranty. They said by the towel rods sticking out from the wall, plus the weight of the towel, would be to much weight.
They said the only way that you could hang anything on a outside wall is if there is a backer in the wall. I ask if there was any backers in the wall, I was told yes, only where something was installed by Jayco.
2015 Jay Flight 23 RB
2014 Silverado LT 1500 with a 5.3 V8 Ecotec3