The length of your bed will only be an issue due to the rear wings on the camper. you will need to block the front to keep the wings from contacting the bed walls. Forward to rear CG will be fine with this larger heavier truck.
Bed rail height at 18" will clear all but the shortest of campers, but you can build up the height with horse stall mats or lumber if you have cab over or side wing clearance issues.
Space between the wheel wells should work well, but you also wan to look at the tailgate opening width. Some campers have bump out behind the the wheel well that can be a problem with narrow gates.
I use the stake pockets on my flat bed as tie down points for my camper. You need sufficient length between this point and the camper anchor point to fit a turn buckle and spring loads. In my case, the short range Torklift FastGun works for me. The turnbuckles should be working against each other or both pulling forward to keep the camper properly placed.
Use a rubber mat in the bed of the truck to keep the camper from shifting and evenly tensioned turnbuckles will ensure it stays there.
