Something like this would probably do him just fine:
[IMG]https://images-na.ssl-images-amazon....ZL._SY355_.jpg[/IMG]

that's all I wear for most of the winter. If it is really cold out I'll slip a heavy pair of mitts on over top:
[IMG]https://s7d2.scene7.com/is/image/Cab...id=460&hei=460[/IMG]

With a flick of the wrist, the mitt is off and the hand is free. For hunting, I use a pair that has a string between them, like kids would have, that way I don't have to pick it up out of the snow behind me.