My 5ver has no warrenty (it's an 07), my frame is not a Lippert and against a lot of opinions, I have an adapter on mine. Pretty much for the reasons you stated.
1.) Truck already had a B&W turnover installed.
2.) I'm a cheap bastard, hence the 07 5ver, bougth as a repo and rehabbed.
3.) I race dirt bikes, hence the Work & Play 5ver. Truck is chase / pit vehicle. Wife is pit crew. If I bonk, crash or blow the bike, it gets loaded in truck. Sometimes by wife alone (depending on how bad I bonked). I did not want big 5th wheel hitch in the bed of my truck, for her to have to work around while loading dirt bike.
Here is the model I used;
Ranch Hitch Universal 5th-Wheel-to-Gooseneck Coupler Adapter w/8" Offset for Short-Bed Trucks Andersen Gooseneck and Fifth Wheel Adapters AM3139