My boss has a pretty sweet setup. No pics, but clever features are removable wood frame bins that just bungee to the sides and store several hundred silo-socks, and a port near the floor to run chest-freezer cords out to a generator. Lots of hooks to bungee things to - lay out blinds, decoy bags- keeps some stuff off the floor and makes it a little easier to get to stuff without unloading the whole trailer.
I haven't done a ton of work to mine, I still haven't put the fold down shelves in it to hold the decoy bags. We put shelves along the front wall to store decoy feet, blind covers, stakes, etc. We also wired it for led flood lights and put a small tractor battery box in it to power the trailer when the truck is off. Also a few clips to hold rakes inside the back door. For size comparison, we have a 6x12 trailer and carry 18 shell honkers, 60 full body honkers, 18 full body ducks, 24 honker silos, a game cart, and 4 layout blinds. The trailer is about 1/2-2/3 full when well organized, which is generally, never.