How durable are composite beds really

Bed talk: In my family: 2 1st gens, 1 3rd gen.

• 2001 DC TRDOR 4WD had the frame replaced, bed underneath the liner is barely there, completely rusted through in spots. Truck is used now as a car camper, bed has a deck and cabinet sliders. No problem, but it could get sketchy at any point. Daughter's truck.
• 1996 AC SR5 4WD southern truck: dirt and clay keep the rust at bay. No bed liner, bed has seen plenty of abuse, hauling logging chains, firewood, motorcycles, mechanics tools, construction tools, etc. It's scratched up and dented but still solid. The Beast. Son's, and now daughter-in-law's truck.
• 2017 DC TRDOR 4WD thrown a lot of logs into it, hauled gravel, rocks, material, antiques, recyclables, garbage and scrap. Now it has a camper top and bed mat, light hauling use only. No problems at all. Dad's truck.

 

Placed the same exact plate the D-ring was welded to underneath. So it's sandwiched with two of these.

 

Good Work. One of the ways it should be done.

 

Thank you.