I would condider Raber, they make the Canadian military mitts with cheek warmers.

You can buy cheap glove liners to wick moisture away and cut the thumb and finger tips of one for delicate manipulating.

Another idea I want to try and is worth condidering is trigger mitts or "shooting mitts", an hybrid between gloves and mitts:



I tried contacting them to know if they have large size Newfoundland wool trigger mitts but I got no answer yet: