^John, I like the way you finished "trimming" it out with the red trim boards.
Happened to have 1/2 a can of that red and it worked out well! Looks better balanced with some colour out back.
That plastic box is bolted to an angle iron frame that has only two large “hinge” bolts about 2/3 of the way back. There is a spring loaded locking latch up front. Even with the weight of all that wood, it’s quite easy to flip down the tailgate and dump.
I have a pile of 1.25” steel tubing that I scrounged some time ago. Thinking the next project might be to weld up a larger “flatbed” style deck for moving around larger stuff……..