I just did the foil tape work a few days ago. I agree that everyone should check theirs (within the AC return and supply ceiling area)...mine needed all new tape. I am hoping this helps with the cooling of the camper.
However, I am still debating on adding a second AC unit, as mine is wired for it, and ducted. For those that have purchased and installed their own...where are you buying, what model did you go with, and did you go with the low profile?
My current one is a Dometic (no idea if its a 13.5 or 15k).