Before I followed the plan and just glued the shear web in the way it is shown there I researched this forum a littleand found a lot of very helpful posts.
I summarized the posts as : most manufacturers tell you to glue the web at the back of the spar. I assume that this is just the easiest way to do it. I also learned that an I-beam kind of construction would be the most effective. Thinking about that I decided ti go with that. There has to be a reason for I-beams being used that much in general construction
It was a real pain to get that right. I ended up measuring between 2 ribs, trying, sanding until I finally had the right fit. I just cut a piece of 1/16 balsa with the grain running vertically ans used the same material with the grain running horizontally for the top and bottom piece. Slow CA to have time to fit it and accelerator once it fits work wonders!
The result is a very solid structure and I am very happy.
I do believe that it has to be a tight fight because of load distribution and I made sure everything fits at least 100%.
I am very happy with the result. I believe it was orth the time.
The advantage of building yourself is that you do not end up with the standard product and have room for improvements.

Cheers

Steff