> All it has to do is supplement the ribs to prevent buckling. <

Hmm. I am no engineer but that has never been mentioned in my reading over many years. I have read that the purpose of the shear webs is to tie the two spars together so that they act as one beam and the ribs don't even have to touch the webs, even if many modelers think that is necessary. Another myth is extending the webs out to the very tip when there is no bending load to speak of there.