Chof16, I hope I can help some.
There is a website called monorpice.com They are great for buying many things audio/video/technology related. If I am understanding you right, you're looking for a mount to keep on the outside of the TT and then be able to simply drop the tv onto, and lift off when done. This is what's on some of the new TT out there. They usually expect you to do this with about a 19" tv. When I was searching monprice for you, I found that they do have a smaller bracket that holds up to a 23" and then I found one that will support up to a 32". This is the link to the one that is 32" and you can search the site and find the smaller one if that is what you are looking for.
HDMI Cable, Home Theater Accessories, HDMI Products, Cables, Adapters, Video/Audio Switch, Networking, USB, Firewire, Printer Toner, and more!
A decent stud finder should help you, but you can also do some pin holes as well. With the weight of a newer style LED 32", if you can hit a stud on one side and get two screws into it, I would feel plenty confident. Remember, you're not running the trailer up and down the bumpy roads with this TV hanging on here. We have a 32" LCD in our bedroom of our Sierra 365saq and I only could hit one stud. It's been up for a year with no problems.
If you cannot hit a stud, I am sure a backerboard will be just fine.
Good luck, post pictures after!