I cock my bow on the ground and haul or carry it up. Without an arrow of course.
I would say you only need one shot BUT I had to reload on one occasion. I think it can be a little bit dangerous depending on what sort of deck your stand has so don't do anything silly AND you have your harness on of course.
The best advise I can give you is to try it a few times from 2 ft. up the tree instead of 20! Most of my backyard shooting is done from stands that I can just step onto at ground level.