Just brainstorming here...and this may be crazy. So...I went and looked at the photos on the DLE 20 thread. Build a strong bulkhead just above the fuel tank where the wing front meets the fuse. (This will take some good measuring. Anyway, on to my idea. Instead of putting the dowels in the wing, mount them facing to the rear in the new bulkhead, but lower than the wing surface as it cross the fuse. OK so now you have 2 dowels facing the rear. Build a cross bulkhead on the wing.... the bulkhead extending above the wing surface. Then drill 2 holes through the new bulkhead that the dowels will slide into. Can be drilled ahead of time....
So to install the wing, you place it rearward of the dowels, line up the two holes and slide it forward until the holes on the rear of the wing match the holes in the rear attachment block. Put in the rear bolts and you are good to go.
Hope that is not too confusing or making it too complicated.
Found a picture that I can refer to as an example. In the picture, the balance blocks of the Cessna would be turned 90 degrees, and under the wing inside the fuse. They extend beyond the lower part of the wing so you can slide them in. If in the right place, the bulkhead on the wing with the holes pushes up right against the new bulkhead above the fuel tank and the rear bolts go right where they are now.