On my 2018 Tundra (what is that, 2.5 generation?), my OEV dealer used an assembly consisting of the stock OEV "donut" bumpers against the bed of the truck, and then a standard hockey puck above it, and longer bolts going into the threaded inserts on the bottom of the camper. That's quantity (10) 1" tall, 3" diameter vulcanized rubber hockey puck you can buy at any sport store.
On my first outing, I found a really cool rock and put it in one of the cavities in the bed of the truck. After some serious off-roading and camper-wiggling, the rock worked its way underneath the camper and got pinned underneath one of the bottom edges of the camper! I didn't realize this for quite some time. It chewed up the paint under the camper, and created a small fulcrum that caused the camper to wiggle in a strange fashion and bend the hell out of one of the puck/donut assemblies, which I now have to try and un-bolt and replace. I really hope it just bent the bolt and didn't do any damage to the insert.
So if you have the camper suspended above the bed in such a fashion that creates an empty cavity between the bed of the truck and the bottom of the camper, such as with the hockey puck trick, be mindful of what you put in the stash spots in the bed of the truck. Things there can work their way under the camper and subsequently get crushed and/or cause serious trouble when the camper is hopping side to side and up-and-down.
