As far as a tonneau cover goes, when the time comes I'm going with an American work truck cover. Retractable tonneau that supports 500 pounds and retracts into a toolbox. Lots of info found online here - Truck Covers USA | AMERICAN WORK COVER
Just a comment on the Truck USA Covers---have had 3 of them on the last 3 trucks... Went with the BIG UWS tool box just because where I go in the high desert on the ranch in far SE NM (south of Carlsbad 30 miles almost on the border) the dust gets into the bed something fierce. Water -- almost nothing they have gutters and drains. If it were not for the equipment/tools I carry including a Pro Eagle Jack which I just mounted the mounting plate in the box this morning that just get covered I would still be using one.. Great for most applications though... You are right about the weight holding of the cover -- you can dance on them
I used CLP to keep the track cleaned and lubed because of the fine dust migration into the track...