Also check Shade Tree power Sports, they have electric insoles that you plug right into your sled. My wife has the cold feet thing going too, last year we bought her some boots from Gander, , can't for the life of me remember what name/brand. I think they were LaCross, they weren't pack boots, they had more insulation than a pack boot. We only rode 30 miles last year what with the stellar winter we had, , NOT, so we really didn't have a chance to thoroughly test them. But, if I can't warm her feet up with those, the next step will be the electrically heated foot beds from Shade Tree Power Sports. Incidentally, they have more than just heated foot beds, they have heated vests, gloves, and a few other things. Only problem I see with that is you have to remember to unplug when you jump off the sled.
My wife is the rider by the way on a two up, so she doesn't get any heat off the engine at all.