Hi Dean--welcome to the forum.
I've not even come close to that kind of project, but had a few thoughts as i read. Box joints are rectangular and offer more surface area for glue, but don't really add any other mechanical advantage. Angling them a little, 7-14 degrees for example, creates a dovetail which would add mechanical advantage.
How to do that?? I'm prejudiced because i've been cutting all of my dovetails with router and jig and now that the light bulb has come on for me--i'm itching to learn how to hand cut them. Your project might lend itself well to the strategic placement of groups of tails--3 or 4 tails, space, 3 or 4 tails, space, etc. Especially if there is some contrast is wood color (which the exposed grain would create on its own).
Tails could easily be shaped with a router and dovetail bit--the waste wood for the most part cut away with a band saw or jig saw to "close" then cut to the line with a guided straight bit. This is where our seasoned members step in for the tachnique, but as i read your idea i had a mental picture!! Can't wait to follow your project!!