Specifically at Gore or Whiteface (two mountains I am fans of), is the sole purpose of carrying so that you don't have to leave it in your car?
Legality issues aside, I cannot think of a single place to store a handgun where it will not pose a threat to you while skiing or boarding. Whether it is strapped to your leg, waist, back, chest, or even a small gun in an arm pocket, any number of scenarios can include a branch, a rogue boarder/skier, pole, or the ground jamming the wrong part of the gun into you, which is going to be very painful.
I've pondered this dilema too with regard to hiding a flask, and I concluded that I'd strap it to my chest. Unfortunately, one of the only times I fell forward on my board happened to be with a flask strapped to my chest, and an ice mogul hit my chest, and jammed the flask in there pretty good. Wasn't pleasant. Now, I actually keep my flask secured between my bindings on my board, but that will be a bit harder to do with a gun.
Just get something like this
The Perfect In-Car Gun Safe - Master Of Concealment.com and lock it to some piece of metal in your trunk. At those mountains, if someone is rummaging through your trunk with a big pair of bolt cutters, rest assured they will be spotted and stopped before the can steal your gun.