RE: phoenix decathlon
Just been looking at my Phoenix Decathlon and a couple of things come to mind.
Look at yours where the two wing bolts go through the wing halves. The factory workers countersink those two holes. I guess the idea is to get the bolt heads down out of the wing. Drag you know..... Well, on mine, they "countersunk" over halfway through the wing. Not a good idea. Those bolts go through a relatively thin area of the wing, and the wing needs as much strength back there as it can get. You may have noticed that lots of wings have a plywood doubler glued back there after the wing halves are glued together. It is there to give the bolts something hard to tighten down on and to reinforce a relatively weak part of the wing and to reinforce the wing joint. On the P.Decathlon, they have inserted "hardwood" dowels back there to get the area strengthening. (and then bored out over half that strength.... amazing) anyway............
Thinking about your two piece mod, the only thing that actually bothered me about the whole deal was how the rear of the wing would stand up. There isn't anything much back there to hold the wing halves in relationship to each other. No 2nd wing pin or spar for example. And where the bolts come through, there is freespace under the wing itself. You might consider gluing in filler blocks. Then the bolts wouldn't be breaking the wing down into the cabin opening when tightened. Or........
What I think I'd do is something like the reinforcing plate bridging the two holes as mentioned above. Only with a twist.
Make a plywood plate that bridges the bottom of the wing where the two hold down bolts go through. Glue it to one wing half. It'll stick across under the other half. Both hold down bolts will go through it. And it will serve two purposes. It should definitely hold the wing halves together. And if you filler block under it, it will strengthen the wing in both inside loops and outside loops, and help keep the wing bolts tight. They'll no longer be bridging a gap. (matter of fact, I think I'm going to fillerblock mine after breakfast. Ought not to take but a couple of minutes.)
Hey, you got a good idea. Would really like to hear how it works for you. I'm betting it works great.