I have been considering fabricating a tonneau cover for my 520. My requirements are:
Vinyl foldable material, no hard, wood or fiberglass.
No permanent modification to the truck bed, therefore; no snaps or fasteners holes drilled.
No attached header rail (placed at the bed nearest the cab).
No support rails.
My thought is to use a bungee loop (http://www.sailrite.com/Shock-Cord-Cover-Clip-Black). This would allow the tonneau to be attached to the factory truck bed loops. I do not know if the header panel of the bed would provide sufficient tension of the fabric when the tonneau is connected to the three sides of the bed.
My inspiration for this project is:
https://www.utecoversdirect.com.au/shop-tonneau-cover/soft-covers/custom-bunji-cord-tonneau-cover-suits-alloysteel-ute-trays/
Please post your thoughts or experiences on installing a noninvasive tonneau.
Thanks,
Keith