I have never had a suction cup stay stuck in a MH.
The day it flew off the window and hit the floor on the motorhome with the GPS rolling on the floor and her saying over and over and over again "turn around when possible"....is when I quit trying to do the windshield mount. :B
I use the donut friction mount. Sticks like glue where ever you put it and what is REAL slick....is you just unplug it and grab the donut and you can take it with you and put it in your toad, other vehicle or a friend your going with that doesn't have one. No fuss.