I have some thoughts:
1 - I wouldn't do a one piece. The 2015 I just bought had a one piece on it and the problems were two fold: a - if you had to haul something that wouldn't fit under the cover then you'd have to take it off. That could be a one person job, with some cleverness, but was basically a two person job. b- then, once it's off, you've got to store it somewhere. Then it's definitely a two person job to put it back on.
Plus - it traps the tailgate. So you have to lift the cover every time you want to open the gate. If it's cold and the latch freezes then you are done until it warms up.
I was in Pennsylvania helping my daughter move back and the furniture didn't fit. I ended up leaving the pickup cover there in the trash because I knew I was going to replace it anyway.
2 - Four folds are probably better than three folds. The smaller sections are easier to deal with. But - here again - if you need the full length of the pickup box in order to haul something then that first section closest to the cab will block you and you'll need to remove the whole cover (unless it is the kind that flips vertically after storage).
My hard cover got damaged and became waterlogged. The interior was a combination of plywood and styrofoam so it didn't hold up. Further attempts to repair it with aluminum sheet were clunkly and didn't last.
Which brings us to today:
3 - I ended up going with a soft rollup. It does what I want, plus rolls into a small area on top of the pickup box panel. Unrolling it allows it to clip into the end of the rails, and velcro holds down the side.
I haven't had to haul anything yet but I see no reason why this shouldn't be fine.
One piece cover shown first (disposed of); roll up cover from the Summit catalog.
https://www.summitracing.com/parts/trx-272401
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