Generally, a bad idea. If the truck is level when towing now, it will sag in the rear when the 5th wheel is hitched up after you install a leveling kit, and the headlights will be pointing to the sky (and into other drivers' faces). You'll also add caster as the rear squats lower - excessive (as well as insufficient) caster can cause caster wobble, also known as "death wobble".
2016 Ram Longhorn 3500 Dually 4x4 CCLB, 385/900 Cummins, Aisin AS69RC, 4.10
2014.5 DRV Mobile Suites 38RSSA #6972
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