other ways to heat while PE'ing
A while back I bought a “USB hand warmer”, which is a cigarette-pack-sized battery with a heating element, selectable between 45C and 60C. It can also be used as a “phone charger.” Not a bad deal for $15, I lay it against the top of my shaft and hold it in place with a rubber band or piece of left-over Velcro from making a Captain’s Wench.
I had an idea the other day and poked around on eBay. They have some “grip warmers”, sold for snowmobiles and motorcycles, that wrap around the handgrips and get wrapped with tape. They work on 12V and have various heat specifications. None of them have the exact dimensions of the heating elements, but they’re flexible mylar(?), waterproof, and look to be around the right size. You could wrap one around your shaft and add a few wraps of elastic bandage to hold it in place. You could use a 12v wall transformer to power them. The prices seem to be in the $20-$30 range for a pair of grip warmers. The 12v part would limit you to the length of the power cord unless you found a 12v battery pack somewhere; I haven’t looked.
The setup LittleEngine has been using is a hybrid of both; a USB battery pack with a 5v flexible heater he found; the details are in his progress thread.