Here is a link to the rail mounted version I have: https://www.etrailer.com/Fifth-Wheel/Demco/DM8550043.html. I don't see the weight listed in the specs there, but I seem to recall that it was 94 pounds. There is also a gooseneck version if you prefer that to the rails, pretty much the same base unlike the Andersen which has a much larger base for the gooseneck version.
I've been searching E Trailer's website for isolators when mounting the Demco Recon hitch to protect the F-100 aluminum bed without luck, so I called and spoke to an E Trailer customer support agent. The agent told me as far as she knows, they do not have any isolation kits for dissimilar metals. Isolating the bed rails would be easy as I can simply add a thin sheet of neoprene under the rails. I'd like to find bolt sleeve isolators and washer isolators for under the aluminum bed. I've seen similar isolators used on natural gas transmission piping where piping travels from below grade to above grade. They are used for cathodic protection.