Maybe this might help you out a little bit. I built a box similar to what you're talking about but posted it on another site. I made it step by step so it's easy to understand. It's fairly compact so I ScrOG it and have been yielding 5.5oz per plant so far.

Grow box
Grow Box Construction - 420 Magazine

Here's the thread of my grows using the box.
Stratlogic's Hydro Closet ScrOG Grow - 420 Magazine

Here's the hydro bucket I made that I use with the box.
Hydro Bucket Construction - 420 Magazine

Hopefully this helps out or points you in the right direction.