First of all, I have a Pullrite SuperGlide in an 03 2500HD.
Secondly, There are
NO hitch support rails. NONE, ZERO, ZILCH, NADA.
Third, Get the spray in and forget the drop in.
As my signature says, I have the PullRite Superglide in an 03 2500HD and
no part of the Superglide rests on the bed as it is NOT mounted as most other hitches.
NO PART. I REPEAT NO PART of the PullRite touches the bed and therefore would not effect a Line-X or Rhino liner. I wish I had gone with the Line-X or Rhino but instead went with the cheap plastic drop in crap. As a matter of fact, the PullRite doesn't even touch my drop in liner and it surely won't touch your spray in.
First thing the dealer does is to attach 4 brackets directly to the frame beneath the bed. Than he drills 4 holes thru the bed to correspond with 4 mounting holes in the brackets. Into these 4 holes he inserts 4- 3/4 inch steel rods that lock into place in the brackets with just a quarter turn. Than he mounts the Pullrite onto these 4 steel rods. The rods actually hold the hitch off of the bed. again, NO PART of the PullRite touches the bed of the truck.
Now when you remove the hitch and the 4 rods there is NOTHING on the bed with the exception of 4 holes. No bed rails, no nothing.