The Banshee wing lacks leading edge sheeting. This is very nice from a crash perspective, because everything can flex when it hits, and it's exceedingly easy to repair. If you have the right balance of wing and covering strength, when the plane hits the ground the covering will burst, and the wing will just break some glue joints.
The downside, such as it is, is that the wing framework is floppy in torsion. This means that all of the torsional strength comes from the covering.
But this lack of torsional strength is yet another advantage -- it's dead easy to fix a wing warp. This is especially nice if you're a helpful expert-ish pilot helping a beginner, because it's much easier to fix a horrible warp in one of these wings than in a D-tube wing.
Bend the wing in the direction to straighten it -- you probably want to overshoot by somewhere between half to the full amount of the warp. For film covering, just reshrink the side that you can get at while holding in the "anti-warp". Then check the amount of warp, and re-shrink the other side. Don't be surprised if you have to take a couple of tries at getting it right -- you're learning. As long as the severity of the warp is getting better each time, you're on the right track.
If you find your plane warping up every time you leave it in the sun at a contest, get a white sheet or a space blanket or something that'll fit over the plane and leave it covered. I used to do this with a grubby old baby blanket with flowers and teddy bears on it because (A) it was in my trunk, (B) I'm lazy, and (C) any embarrassment from using such a blanket is less than the embarrassment of letting your plane get visibly warped up between the morning's flying and the afternoon's flying.