What do I need to know about purchasing a hitch?

I use the Sidewinder with my short box truck along with 2 other camping buddies. The hitch is under 100lbs and I can remove it in 5 minutes to give me a clean box. This setup is approved by Lippert (which makes the 5th wheel frame) so that my warranty is not voided.
Apparently Lippert won't warranty the frame with an Andersen however Andersen themselves provide a great warranty. I really like the Andersen setup as it is only about 40lbs but I don't think it will work 100% with a short box truck.