Someone commented that the operators must be looking through a gap between the gun and manipulator arm... I think they might actually stand when using them. Just a thought...
However, I do think that the original idea has been thrown right out of the window. They were meant to be alien and look like no normal human could get in there. Which is why Ian Chesterton had trouble getting into the Dalek shell and they had to hire really short people like John Scott Martin to drive them...
"The producers always liked the Doctor to be able to look them in the eye"

?? BULL!
-Marc