Details

A carbon fiber spar should be added, likely intersecting the extreme rear of the main compartment. The main compartment may have the rear wall pulled forward such that the spar is submerged, or the spar can be exposed by retaining the current compartment geometry.

Ideally, the spar would be along the quarter-chord, but that would intersect with the battery. The OML would have to be altered to allow the spar to pass either above or below the battery, but if adding the spar along near the rear trailing edge of the wings is enough, then no need to rework the entire vehicle geometry.