Something that has not been mentioned is the height of 35" tires may make loading and unloading of a truck camper difficult due to the height. The GM's will not fit 33's without modification or a lift kit, so I assume this truck is sitting on tall tires and a lift.
These 35" tires may not be rated sufficiently for carry a camper with all the features that are desired and you may need to scale back your wants or go to heavier rated commercial tires.
Your lift may may also not be the best choice for hauling a camper. Many are designed to allow for more wheel travel by using softer suspension components. This will result in unwanted sag and sway when loaded.