Wing Analysis

Here is the negative 3G case. The struts do not take any load. The required spar cap sections in unidirectional carbon fiber are:
Red - 60 mm2
Orange - 40mm2
Green - 30mm2
Light Blue - 15mm2
Dark Blue - 6mm2

We need to use for each spar cap, the larger of the two sections for the 6G positive or 3G negative case. This means, basically, tapering from 60mm2 at the wing root (required for the 3G neg case), down to about 35 mm2 at the strut attachments (required for the 6G pos case), and then tapering down to zero at the wingtip.