What kind of truck do you own and does it have a live/solid axles or independent? I was going to say that uneven tire wear is unrelated to the camper, that it is due to alignment/suspension. The argument could be made that the camper impacts that though. You would only see that with independent suspension though, and only under the most extreme cases. An inch to one side or the other will have no discernable impact. Your uneven tire wear is not related to where the camper sits on your truck.
ETA: Looks like you have a Ram 2500 with solid axles front and rear. Your front tire(s) is probably turned inward, the toe needs to be adjusted. I've seen this on Dodge trucks in the past. You might take your truck to a shop to have the alignment checked. Wear on the inside/outside is a toe issue and should be easily correctable. Suspension has a lot of parts associated with it. Not really difficult to understand, but a number of variables. Without getting into the moving parts, you can get a good understanding of caster, camber, toe-in, etc and then understand tire wear or odd handling, especially over varied terrain. It's kind of a fun part of the mechanics of vehicles.