What do you do for tie down points on your flatbed?

[79vette]

I put an underbody tool box on my 88 C30 today, and I had to mount it flush under the bed for ground clearance. I used to use wire hook straps sort of jammed under the edge of the bed rail, but that was kind of sketchy and I had one pop off once. With the toolbox now I couldn't use that strap type even if I wanted to. See picture below.

I have a ton of snap hook straps and stake pocket D rings I use with my trailer, and I really like those since they don't come off even if the strap becomes loose.

I'm thinking about adding stake pockets and rub rails like I have on the trailer, but that is pretty heavy and kind of a pain. I'd like to keep the top surface of the bed flat for any oversized cargo, so welding d rings to the top surface of the bed frame is out. What would you do to safely attach tie down straps to the truck in this situation?