How do I haul a TC while still having the 5th wheel rails?

I pulled the bed liner pulled out tonight. The distance between the wheel wells with the bedliner is exactly the same as the width of the camper. So, the bedliner had to go.
I then laid a level across the 5th wheel rails and took a measurement for the how thick of foam board I'll need. It's 1.5" so I'll go for the 2" foam board for a safety margain.