the boxes are actually bolted down, the straps are just there for whatever.
I used a couple of the inserts on each box, a round (button head) allen bolt and a large fender washer.
They actually come off fairly quickly too.
Im still experiementing with different boxes and how they sit/ride on the machine, too.
The plano crates were about $25 apiece.
I have the front rack rail as well, and I'm rolling over in my head something to hold the extraction gear up there (rings, soft shackles, hard shackles, tree strap, extension line, etc) where the winch is.
I've actually used all of it at least once, either skidding logs or pulling me out of oopses.