[wingnut60]

A lot of new pickups sit higher and have a deeper bed depth than previous years. This causes the fiver to sometimes be nose high when towing and when that is the case, clearance at the rear of the bed becomes a problem. In sharp turns, especially off-level, the underside of the fiver may come in contact with the truck bed corners/tailgate.
If this is the case, two solutions: lower the truck or raise the trailer. If you want to raise the trailer, a spacer tube (riser) is placed between the frame and the suspension. 2" is common, sometimes even 3" is needed.
Most hitches have some adjustment to raise the mounting plate to help with this, but this also raises the front of the trailer causing nose-high towing and possibly excessive weight on the rear axle/tires.
If you have a standard spring suspension, most any competent spring/axle shop can do the work; if your trailer has the Morryde Independent Suspension (IS) than it is more difficult to do the work correctly unless done at the MR factory in Indiana.
Depending on your truck make/model, the extra work may or may not be needed. Some trucks 'squat' more than others that will help alleviate this off-level situation.
Best suggestion is to research the trailer owner forums to find someone who already has your exact pickup and see what they have done/not done about the truck being too high at the rear of the bed.
Normal needed clearance between trailer and truck is around 6"--more is better as long as the trailer sits nearly level when hitched.
Long-winded explanation--hope it helps you.
Joe