Just like the largest wind turbine blades are not solid, so would the largest airplanes not be. So this would not hold I think if I understand you correctly.
I think a probable design for a giant wing is some sort of rigid or semi-rigid envelope around a pressurized chamber, probably using that “tensairity” principle, composed of multiple sections so that even if your parachute or other safety mechanism failed to deploy, you wouldn’t lose the entire wing in a crash. You could maybe even add crumple zones. You would I think want to look at the thickness vs length of the wing so that the wing is more resistant to bending, but wouldn’t that also reduce the efficiency of the wing?
Why is that? Because of higher wing loading? Because of the wings being designed to work better in higher speeds for example?
You want your wing to fly fast, right? To reduce material usage? How fast?
I think the question is too vague. More useful would be: what are all the ways that you can imagine building a wing, and how large can you reasonably make that? How much would those cost in material? How much power would each of them be able to extract from the wind?
The question attempts to get a quick overview of the thing by asking about everything at once. That’s too wide a question to reliably give rise to useful discussion. Better to ask about every single thing separately. [1] How big can you make this? [2] …? Slow down to speed up.