I was at a dealer a few weeks ago and while I was there a guy pulled in with a ram with a fixed mount gooseneck ball in the bed. He had just purchased a 40ft toy hauler 5th wheel camper. He slapped this adapter onto the 5th wheel king pin in about 5-10min, hooked the rig up and left with it. I have no idea if he planned to use this set up full time or if he was going to replace the entire 5th wheel king pin on the camper with a gooseneck hitch after he got it home. I do know that he said he was ONLY going to tow it with the gooseneck ball because they go out in the wilderness with 4-wheelers and the gooseneck is more forgiving of uneven ground than a 5th wheel. Especially when trying to disconnect or hook it up the camper.

When we were camper shopping I decided I didn't want 5th wheel rails permanently mounted in my bed.
So I bought a Curt Gooseneck under bed hitch (similar to the BW hideaway) and a Curt 5th wheel adapter that slides down into it when you pull the ball out. I heavy sob, but you can pull it out in 2min and have a flat bed again. Any 5th wheel hitch works in the rails of the adapter... but it is weight limited to 20k lbs.
Curt X5 adapter , Double Lock EZr Gooseneck

So after I bought all that stuff, "The Wife" picked a new camper that is "technically" puts my 2500 over weight limits. With the firestone red airbags it would pull it all day long & not squat, but with the pin weight of the camper plus the added weight of the gooseneck+adaptor+hitch... the truck would be sitting around 9800 lbs (9k gvwr)... I didn't feel like being held "at fault" should we get in an accident some day... So I went south and bought a rust free 2004 3500 dually. It has a set of Reese rails in it already, & since the holes are already in the bed I'm not taking it out to swap in the gooseneck set up.
I month ago I had a plan & a truck I trust to go anywhere... now I have a gooseneck hitch and a 5th wheel adapter sitting on the floor without a home, & looking at selling a rust free truck I love & trust... while hoping the new one is just as reliable.
I guess that's why some guys stay single.