You asked about the risks. Looks like the cabover is riding on the roof the only fix for that is to raise the camper in the bed which will really make the whole thing tippy. It is sitting so far back that is going to really wear your tires out. My two biggest concerns for you would be how unstable the truck is going to feel and are you going to be able to stop in an emergency. That rear jack looks to be at an angle which means that the mounting screws are not tight; could be dry rot. I also don't see where it is even tied down at the front. Looks like a $500 camper with a newer coat of paint. If you can get out of it or even take a small loss/deposit I would run. Just my two cents. P.S. the guy with the guitar is smiling because he's hoping somebody buys the thing without looking at it first.
