cheeze1 - Don't have my unit at home, its at my storage building out of town. Did you get a wireless? Seems like the outside sensor should be wired into your backup light circuit. When you take off your tail light assembly, you should see the color of the wire going to your backup light. You might be able to splice into that wire. The receiver (beeper) on the inside could be connected to the line going to the cigarette lighter....or actually powered by the lighter socket - makes it more portable. I might study the fuse panel and see if I could jumper off one of the circuits that power things like radio, dome lights, running lights (they call them something like DSL). Radio Shack normally sells little jumpers that you can piggy back onto a fused connection.
F250GulfportFlorida - I already had you on my private list of Trail-Lite B+ owners. You were number 68 of 75. Glad to hear you are liking your unit. I still think they are the best built units for the money - a real value.
We probably should consider a get-together of all the B+ owners. We are a little unique in that most of us sleep on dinettes or sofa's since we do not have overhead bunks. We also are usually shorter and narrower than our other Class C owners. What a riot having 75 B+ owners in one campground.