DO NOT USE THOSE HOT HANDS.... those things get very very hot and can very easily burn, i know from expierence because i used to throw them in between my gloves when i rode my motorcycle into winter, gotten burned a few times with them and i had a layer of material between my skin and the hot hand...
nope. not gonna use them.
what about those reptile shipping heat packs? Uniheats when in a pinch?