Since my first trip where I took a kudu, impala and a piggy, I have switched from 35-55 GT with 250 upfront cut to 29 inches ( weight of 500 with hunters and 540 with trad gt) to 55-75 gold tips cut to 30 inches and more weight upfront, 300 grains, to get the same same spine but with a higher arrow weight without weight tubes. (About 600 grains with 55-775 hunters) I'm shooting 50 lbs at 28 and the heavier arrows fly just as well if not better with more penetration and a quieter bow.
I agree with BTH, I shot for months out of a 8 X 8 inch hole in a plywood board at targets arranged 10 to 18 yards away from the set up before going over. The practice paid off and I probably would have been lost without that preparation.
Practice alot in your cold gear because the mornings can be cold. I'm considering bring a dark colored wool blaket to wrap up in the blind so when the moment of truth comes, I can slip off the blanket and then shoot as versus wearing tons of clothes. Just a thought. You could never get away with that in a tree stand or stalking but the hides afford you alot more cover as long as you are quiet. You will love it there. Bhill