Some thought or past experience has gone into that I'd say. Using the two boots in series to give a longer pull is pretty clever.

That was almost-standard in 1920s-1930s.

A rubber cord, a single felt boot (since most propellers were two blade), two-three men: one holds the propeller, others pull the cord. When they can't pull it any more, propeller is released.

Main problem was to warm up the engine in winter. For liquid-cooled ones that was done by repeatedly draining the system and refilling with hot water. I don't remember what they did with air cooled ones, maybe a blower of some kind, or just a blowtorch to the cylinders. There aren't many options on a snow field out somewhere in nowhere.

Brave. That could have been some really bad rope burns or worse if the rope got tangled.