I imagine the gunner in the T-70 is actually a very well trained monkey, who is using both his hands and feet to load and fire the main gun and machine gun whilst tracking the target with the turret. The man that pops up in recon mode is actually a puppet with a periscope inside to fool the Germans into thinking the Russians don't have highly trained tank monkeys.
i like this answer. the monkey would have to be strapped into the turret in order to be able to use all four limbs though, but that's doable.