Not sure which 5th wheel trailer to purchase

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I recently sold my 2002, 2500HD 8100 big block and trailer. I purchased the 2019 Silverado 3500HD Crew Cab duramax LTZ standard bed, single rear wheel, because I wanted to buy a larger 5th wheel toy hauler, 42'- 44'. I have never pulled a fifth wheel before. Every trailer and truck salesperson say I picked the right truck and would have no problem towing the big rigs. The trailers I am considering are: Highlander HF383H, Keystone Impact 415, and the Keystone Fusion 419.

Just wondering if anyone has, or knows someone who has, a similar setup and if they have had any towing, suspension, or power issues? If so, what did they do to fix them? Also, I would appreciate any suggestions on how to beef up the truck to safely handle these big trailers if possible or needed. I live in Utah so I would be pulling steeper hills and off road. Suggestions please? Besides buying another truck.