If the wing covers had extra material sewn in -infront and behind the wing proper- with tie-down points on them, would this help?
The result would be a ground bulge, not a wing shape at all.
This would prevent air going under the wing and taking control.
I cant imagine it would cost too much, there would be less rope to store as well, just peg the eyelets straight into the ground

just musing

bagger