BG6: I admit to an interest in the portable units from the standpoint of no possibility of a leaky roof. Are these like window a/c units you would put in a bedroom window? Any more info on them I'd appreciate it.
No, these are a standing unit with a length of dryer duct to pump the heat outside. You put them where you want them, move them from room to room, etc. They are about 24 - 30 inches tall, 18 inches wide and a foot deep. I don't see any reason that you couldn't hang them on the wall if you wanted to.
I've been seeing them at my local Costco for a month or so for something like $400 each, and they are at the big hardware places. I wouldn't be surprised if they are also at Walmart, so just call around and you'll find them. DO NOT say you're putting them into an RV -- if one goes bad, you don't want someone saying that you caused the problem.