David,

Not fully sheeted wings does have the problems of the distortion of the airflow over the airfoil. Round holes in the LE does generate two more points and curve of distortion on different areas over the part of the wing with the highest differential pressure.

Better is cap strips (or square holes as you write) so there is only little distortion near LE and Spar and less on the critical locations.
For this reason in a lot of open wing constructions even the spar does not touch the covering. Look the WW1 planes.

When you want safe weight with the shear webs, give them less surface, for example 50 % of the normal distance between the ribs and more less in direction to the tip of the wing (hope you understand).

In all cases, fully sheeted is more accurate for the airfoil and that was the reason we already see this in 1964 also on the Taurusses.

Cees