grab a small duffle and pack it as a boot bag, then bringa backpack too. I always pack pants, jacket, boots, helmet, gloves, goggles all into my mini duffle as a carry on. Then I have a backpack too with some rando shit, then my ski bag as the only checked bag.
I've never seen anyone hassled before by the size of their duffle, so to avoid having to pay at a last resort carryon it on with you. Also if you pack all the stuff you need to ski besides skis, ifyo shit gets lost, then you can just rent on day one instead of having to miss a day because Delta fucked you over