SDcampowneroperator wrote:
Most certainly your camper is not aluminum 'framed'  but  aluminum superstructured.  The frame is steel. Check it with a magnet.
  Using a  goose neck adaptor on a  rig  designed for 5th wheel adds a lot of leverage to the frame. The pin box attachment frame is not designed for that added stress.    Warranty will be voided. 
   It is a PIA to have a 5er hitch in the bed of the truck, but I feel it is offset by the ease of hook up.
Good info.
Contact the trlr mfgr's Tech Line and ask - way better info than an internet forum..:S
BTW - how long does it take to remove/install your 5th wheel hitch?
(Mine takes all of 5-10 minutes to a "clean bed".  No big deal)
.