r2m
Richard
When I had my F350 crewcab overlander, for the back I used a rubber backed indoor/outdoor carpet.Ha, that's a mountain outline!
Yup, 25 lbs is definitely ok. We've never seen one break, but I'm tempted to do some destructive testing just to see what it takes to break one. We tested up to 45 lbs and you start to get some flex, but I think it was a long ways from failure. It's aluminum brackets holding aluminum rails so it's a sturdy thing.
Keep in mind the sleeper spacer is more of an aesthetic thing. Once you toss a sleeping pad on top for sleeping and lay on it, it all stiffens up. Functionally, it's totally fine as is. The spacer concept just eliminates that visual bump and unweighted movement.
Grocery getting: For large items, it's great. Costco runs are fantastic. For lots of loose small items, a tote or a universal all-weather mat goes a long ways. We played with various bedliners previously and while very durable, most of them stink (polyurea is a significant health hazard during application and can off-gas for a long time - not ideal for an enclosed car cabin), they're annoying to clean unless you can powerwash the surface, and some of them are abrasive enough to snag on the less-durable performance fabrics. Carpet is great... until you spill a beer, cooking oil or some other not-water liquid. We've carpeted a few systems and it's nice to crawl around on and keeps loose cargo quiet, but I'm not sure it's the best solution.
For my daily use, large items are great in the back on the platform with or without sleeper. I carry some "Snatch-its" and use those to hold gear down as needed. Small items generally go in the second row or in a drawer.
Considering we're at the beach, snow, camping, etc. it worked great! Just pull it out and hose it down.
The rubber backing kept it from sliding around the bed of the truck when we had stuff on it and added to a little padding. The carpet topside was great as it too added to the padding and kept "stuff" from sliding around when driving.
I just purchased it at my local Lowes.
In short, if I were to do your setup, I'd just go with the same material I used in my truck. Simple, cheap, easy care and works.