We read @faithie999‘s post about the 3M 77 from several months ago, and it was very informative. We debated long about the best solution for us. I will say the 3M would absolutely be the most cost effective. We ultimately went with the Velcro because we intend to cover each panel with some sort of cloth to hide any nicks or scratches that will inevitably happen. There isn’t a timeline for that add-on, so we erred on the side of caution for an absolutely removable option.
As for a sunny day melting the adhesive, it could be possible but I’m not convinced (yet – although I admit my local temps are currently in the teens). The adhesive is very strong as it is marketed to hold tools, presumably in an outside shed which would be subjected to the same temp changes as the camper.
In the end, if it does melt off… then I get a second shot at it as will probably go with 3M.