Tool chest/box (no bolt) bracket.

I am looking for suggestions/opinions/ideas on this 2 piece bracket. i drew it up, i am no professional so bare with my drawing.
Pic 1 is the view from the rear standing at the tailgate.
Pic 2 is a side view of the bed of the truck.
The tool chest I am looking at is the
Dee Zee Specialty Series Large (40 In.) Poly Chest Tool Box
Part # DZ6537P SKU: 247225
This Box is 99.00 at Pep Boys
or something similar that will leave space on either side to allow for hi lift, shovel, etc to utilize the full length of the bed.
Also just slightly lower than the height of the bed itself for a stealth appearance.
I prefer nothing to be on the edge of the bed incase I install a best top style canvas fabric style top on it or any other top that utilizes the top edge of the bed rails.
The only bolts i would use would be bolted dirrectly into the tool chest itself indicated by the circles on the drawings.
once bothe brackets are in position the tool chest itself will act as the connecting piece making it one solid piece.
If anyone has something similar, or works with metal, or even if you see something i missed i would appreciate your input before i proceed.

 

I'm like you, my drawings look like some chinaman did them. However I'm still trying to figure it out so no help yet.