It sounds to me like you're best off passing on this unit unless the price is really, really good—which, despite your first sentence, doesn't seem to me to be the case if you're looking at a loan for it. I'd suggest that you have no motorhome you can use and no loan payment, rather than a motorhome that may well prove to be unusable due to needing significant repairs and a loan payment to boot.
Scratches and dings, if nothing more than that, are in themselves just cosmetic flaws. A lot of them tend to indicate that the unit has seen hard or rough usage, and so could portend other things wearing out. Separation between the floor and wall, particularly if an outside wall, suggests significant structural problems. (If it's an interior wall, the wall usually isn't part of the basic structure so it would not be quite so concerning, but it is something that needs work.) Jury-rigging can be good or not so good, depending on the jury-rigger, but probably tends towards the not so good if it stands out as such.
New tires will run you about $1000. Slide repairs can be costly, if needed, but it's impossible to know what's up without investigating what the source of the noise is. If the engine and drivetrain have received proper maintenance, they would be the least of my worries; the Ford (and Chevy) chassis are reliable and regularly go for many miles in commercial service. Other RV systems can also be costly to repair or replace...I don't know how much of everything you checked out thoroughly. EDIT: I also want to be explicit that all bets are off on the drivetrain reliability if not properly maintained.
