Well, I have about five or six inches cab clearance, and my TC was laying right on the rail before I stacked it on the decking ... I couldn't even squeeze a sheet of paper in there.
So, regardless of what Lance says, in the generalized statements - I believe those dimensions are inaccurate - I'm sitting here looking right at my truck with the camper on it. One thing too, the bed rails have those composite protectors on as well, so that could be 1/2 inch - not sure. But this is just a heads-up to look at it before you damage your TC accidentally.
Now it has a 3/8" bed mat and a 5/4 decking, and it appears right about at one inch clearance. It's raining, so will check tomorrow again, and mention it here if different - unlikely tho'. It just pays to check it ... :) :)