zippo lighter fluid works GR8 not oily like wd40.
If the tape is behind something you apply fluid then use dental floss and work it back and forth and down like a saw blade.
Over the years, I have come to love the smell of WD40 and Three in One Oil -- I know that's weird, but I think it's because those are workshop aromas, and my workshop is where I go to have fun, after working at my desk all day. So it's one of those Pavlovian conditioned responses, I guess.
But since DW does not share my bizarre tastes, I agree that it is not a good idea to stink up the trailer with those chemicals!
You can use a product such as "Goof Off" which can be found at Walmarts, Lowe's, Home Depot and most hardware stores. It's specifically made to remove adhesives. Just be sure to test it in an inconspicuous part of your trailer to make sure it will not do damage to the wall. Good luck.