All 4 “should have” some sort of spring in them. Weather frame mount bumper mount or bed mount tie down locations.
Anything from a chain and hardware store turnbuckle or a 2” ratchet straps will get you home, but with no relief in the tiedowns you risk bending something or ripping a camper mount off when you hit a large bump or twist the truck frame much.
That said just cheapo turnbuckles and chain work fine but need a spring. Either in the tie down or on the truck side mounts like the little ones torklift sells.