@William810 A one-night stand that pays for multiple nights doesn't sound all that bad for hosts, but of course one must handle the linens carefully and make sure the mattress didn't get flipped.
@Leslie682 I agree, no refund is warranted here, and it's best that you don't even bring up that word. Personally, what I would do is first inspect the RV, and if everything looks good, I'd write back to thank them for their stay and suggest that they're welcome to a "returning guest" discount if they'd like to have a longer stay next time. (Statements like this are non-binding, but a great final impression would be a big boost to your very first review).