I had previously posted installing 1x6" shims at the wheel wells in my Ford F-150 because the camper was "walking" sideways 1/4-3/8". I have since added a 1/4" piece of lath on one side in addition to the 1x6" to remove all the space between the wheel wells and the camper but NOT wedge the camper into the bed, 1/16" free space remains. 1 or 2 turnbuckles needed to be tightened every 1,000-2,000 miles before the wheel well shims were installed and I have only tightened one turnbuckle in over 6,000 miles after adding the wheel well shims. In addition, the camper is not "walking" sideways with the shims and instead remains centered. I suspect the one turnbuckle tightening was needed to settle the camper against a shim because the one adjustment occurred early in the 6,000+ mile term. The shims are not attached to anything and are installed after the camper is completely on the truck. A bed mat was not a preferred choice because the camper is on full time and the camper floor is well drained and completely dry without the mat.