One of the skills that working on Air Force aircraft was the 1 handed seeing eye dog. That critter has let me get to more fasteners than I can remember. He was a b&^%h to train though. That bolt is the only thing securing the front of the glass and the wing window when the door is shut. If you leave it out you could crack the glass when the door is shut. It may also "cock" and jamb when it is rolled up and down. I would use it. Just my 2 cents worth. If you put your arm into the door to the elbow towards the latch end of the door. Then turn to the up direction you can get there. Keep some bangaids close, you will skin your self somewhere.
