I'm not one of the cool kids who do AIWB, so I'm looking at things from regular strong side carry perspective. That said...
I've been playing lately with waist-length jackets with elastic waists. Yank the jacket up, it should drag any layers underneath it and over the holster up. The issue is, depending on the amount of stuff you wear, you might end up with a bunch of bunched up fabric forming a "ledge" of sorts above the grip of your gun. Still though, I find this a lot better than a lot of the usually mentioned options. You can actually wear a jacket fully closed with this method, for example.
(Although to be honest, if it's really cold at the range, I'm typically more likely to switch to a dropped and offset or dropleg holster. Doing lots of draws from underneath a jacket is a good way to lose a lot of body heat. (A waist-length jacket is neat with these open carry holsters as well though, since the jacket is short enough not to get in the way of the holster.) So, I admit I don't do as much reps with winter concealment that I could, but... Screw that, it gets cold. )
That caught my eye as well. Better to have the outer layer loose enough that you can just pull it up.
Glove liners are really, really great. Super thin little liners that, when combined with a "meh" winter glove keep your hands much warmer than a single glove layer could. And since they are so thin, you really don't take much of a dexterity hit with them. Much recommend.