1) I would put the bed platform on the passenger side. This might not really make any difference but I would rather not sleep on the side of traffic when stopping for the night on a highway pullout.
2) I would have put some insulating foam down between the box and plywood
3) would have used 1/2 min or 5/8s plywood for the box tops rather than 3/8s
4) framing in the boxes was kinda jankie, I did it on the cheap with as little material as possible. I'd take the time and do it right next time.
5) draws would be handy
6) I would build it on a better platform, the truck is pretty close to the end of it's life, it's sitting around 300,000km. Also having 4x4 or even positraction would be nice for going /out/.