What Andy is describing is a TC that is not being held down evenly on a flat surface. The fact that the cab over is touching the truck cab also shows it is sitting too low in the truck bed or it is sitting on something that compresses and is spongy.
I would start by by making sure the truck bed is flat and is not crowned in the middle like some GM models. There should not be a plastic bed liner in place because it compresses and slides around too much. With a rubber mat in the bed, you should have a couple of inches between the truck roof and camper to allow for frame flex when traversing uneven ground. If you do not have clearance, one or two sheets of high density foam insulation sheets under the bed mat should help. If this not enough, a wooden platform needs to be built under the camper to get sufficient clearance. Now that we know that the camper is on a secure base, it needs to be tied down. I prefer a spring loaded turnbuckle with even tension on all four corners - Honestly, this is hard to achieve unless you use the lever style turn buckle or you have an exposed spring where you can measure compression. There are a number of tie down brackets available but I don’t recommend any that attach to the truck bed on the new trucks - The metal is just to thin and will bend or buckle over time. Find a way to attach to the internal bed anchor points or attach a bracket to your truck frame.
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