I read a great tip on this forum a few months back (thanks to whoever it was) and I use it every time I make vortex wings. You gotta let the wings "cool" for about 10-15 minutes by taking the lid off the kettle, but leaving them on the grate. This will prevent the steam from the wings wetting the crispy skin, which is what happens if you take 'em right off and bring 'em inside. They'll still be too hot to eat but it seems to do the trick to keep the skin crispy. (also, letting roasted Brussels sprouts "cool" slowly for 20-30 minutes in the oven after turning the oven off seems to have the same effect on keeping 'em crispy too.)