Chevy 3500HD Duramax Diesel Stand Box (6-1/2') & 377MBS Hitch & Pin Box Dilemma

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Truck is a 2019. Dealer recommended a PullRite Super Glide 18K hitch and the 377MBS came with a RotaFlex pin box. SuperGlide was installed (works great), but came in contact with the tonneau cover rail on a sharp turn, which sits about 1" above the bed rail. So we install a PullRite "lift" rail system under the Superglide, which gave the additional clearance needed. The "lift" rails added an additional ~3" of height. HOWEVER, now the 5th wheel sits nose high. The pin box could be lowered (2"), but then I'm back to a clearance issue on tight turns. Any advise?

[huntr70]

Yep, lose the extra height from the cover or tow it slightly nose high.

[Paedea]

Get a. Trifold tonneau cover for $350, you don’t have the 1” rail.

[Hwktlg8]

We have the exact setup as you same rig, same truck (no real changes from 17-19) and same hitch. Our tonneu cover is a roll up access brand cover that migrated itself over from a previous 2015 gmc. We have had no issues at all with contact between the pinbox and cover rails. We do not have any “lift rails” on the hitch and use the oem puck system.

[mgargiullo]

2017 GMC 3500HD with a hard roll up tonneau cover, using a B&W Companion hitch on the highest setting without MBS377. When I get close to 80-90 degrees, the pin box mount hits the bed rails. I already have the hitch at it's highest position. The pin box is bolted to the 5th wheel with 5 bolts on each side, 3 in front, 2 on rear. I could drop the pin box down one, which should carry the 5th wheel slightly higher in the front, but then it would only have 4 bolts per side. The only other option I can see is swapping the pinbox out for a shorter version so it can pivot a full 90 without touching the rails.

Thoughts?