Far as I'm concerned, a roof rack is a waste of weight. The one that came on my Lance is VERY heavy. At least the black beams I could remove. The permanent mounted silver arms are just as worthless and they help trap water on the roof when I have the winter cover on.
Putting anything on the roof is asking for trouble. The weight up high is going to cause a lot of sway compared to weight hung down low. If you can't fit whatever you need inside the camper or truck, then get a small tow trailer. Putting******on the roof is also going to bite you in the ass when you forget and wipe it off when you don' clear that tree branch some day.