I ordered the factory 5 th wheel on my 2015 F 450 . Puck system is the best. Reese 26.5K capacity pulling a jayco seismic 4212 that is maxed out when loaded. As for pulling with a gooseneck set up, no way for me. Pulled doubles to Alberta and changed every gooseneck to a king pin every trip. Tried it both ways and put on 40,000 miles and king pin is the best for safety and comfort.
As for the Lippert frame warranty, I would check again on warranty. 2 5/16" gooseneck conversion changes all the stress points and I have been told in Elkhart not to do it.
2015 F-450 XLT 440 HP Power Stroke 26.5K Custom Resse F/W, Manual Regen, 19.5 Rubber
2014 Oreion Sand Reeper 4x4 Toy steel everywhere, street legal and licensed, 5 speed manual, 3 cylinder DOHC "Chery" engine and 2 door fun.
2015 Jayco Sesimic 4212 Extreme Weather Package, Dual Pane Windows, Side and rear Patios, 480 watt Zamp Solar Pkg 6 AGM batteries, Residential Fridge, custom Dishwasher, 5500 watt Onan and lot of problems.