Learn to shot from multiple positions, if I'm blind calling I seldom stand the whole time. You can get away with a lot of movement with elk, I don't hold my bow until I need it. I don't nock an arrow until I see elk and know I'm going to be shooting. I've never missed an opportunity from not having an arrow on the string already. If I'm standing I normally set my bow on the ground by my feet or set a cam on the front of my shoe.
A friend made some hangers that attach under their quivers and stick out past the string and hook to a belt loop or pack, they gave me one but I didn't want the extra weight on the bow, something like that would work well also.