Dom,
As Grump said, you can do better than that.
Among the things to roll into your spreadsheet with this operation is that even if the vehicle has only been driven 15K miles, a lot of the rubber parts will be shot. This does not mean just tires. Tires are a given, plan on replacing the set. It also includes all the hoses, belts and things like the rubber brake line and maybe some wheel cylinders. Don't go anywhere without flushing both the brake fluid and the coolant.
Other thing, if you see any evidence of water leakage, walk away. It will be a money loser even if it is a gift.
Remember, what you are looking at is a truck with a travel trailer (read less than code house) stuck on it.
Can you even get a good old coach? Sure, I know lots of people that have them. Mine is over 40, but there is also a running line in our group.... A reliable ready to travel coach will coat 25K$. All at once or as a kit..... It seems to prove right most of the time.
Matt