Sorry to hear about the damage. :(

Typically 6 inches or so clear is recommended between the truck and the underside of the 5th wheel. Usually there is adjustability in the hitch, kingpin or both to achieve that.

If you have a Pullrite Super Glide hitch and rail system, Pullrite offers a 3” lift kit that is easy to install over your rails. Pullrite 4408.

Hi, I agree with Greg F. But one other note worthy item to watch for...when going over short but steep hill - up then down quick - like some rail crossings...the back of the truck and the bottom of the fifth came come close together or in close contact. Watching this and adjusting your angle of approach and departure can help ie take it at an angle if possible. Also, if you have adjustable air bags on your truck you can adjust them on the fly to give you more room. Hope this helps you figuring out this challenge.

I think Ray had this problem also a couple of years ago when they got the new Ram. Maybe he's got a video of what he did to fix it. Many of the new trucks ride higher now according to what I read.

Mine didn't turn out to be a big problem, especially after the new truck springs and shocks settled a bit, the only time it gets close to touching the bedrail is when off-roading and a deep rut twists the fiver sideways compared to the truck, I just have to take it slow and watch it. But I don't have the 8 foot fed and no cover.
Best way to solve it is raise the hitch and the trailer suspension to gain at least 6 inches of bed rail clearance. Seems to be the magic number, though 8 is better for off-roading. :)