I don't have a cargo door on my Elite, but on my battery box door there is a cable. One side is riveted to the trailer body and the other has a small aluminum plate that has been tapped for two screws to hold the steel 'catch' to which the cable attaches to. The aluminum plate is then glued to the door. Sounds like your door has insulation on it? That could be a complication but if you have an aluminum plate like I do and it has come off the fiberglass door, then I would use this adhesive to glue it back on:
http://www.westsystem.com/ss/convenient-repair-packs-provide-a-quick-fix/
All this may or may not apply to your situation, but just in case.... Prep the area well. Get all the old adhesive off, sand the area well including the back of the plate, and wipe down with MEK. I would also drill a few extra holes in that plate to act as keys for the epoxy when you glue it back on. You could even countersink the holes just a bit (on the unglued side) for a dovetail effect. Use the adhesive filler that comes with the kit when you mix up your epoxy. West System epoxies are great products and are available at West Marine if you have any in your area, or probably even on Amazon.
It is kind of a difficult design problem having the door drop down like that. What Oliver need to do is glass that aluminum plate right into the door when they make it. Relying on adhesives after the fact is not so great a long term solution. Good luck.
Dave