There are a few tips for backpack fitting that will help you suffer less on the trail. For starters, keep the densest, heaviest gear centered in the lower third of your pack where it’s close to your lumbar spine. Once these things are loaded in the lower center of the pack, they can be wedged into place with clothes, smaller gear items. Keeping things centered is crucial, if your balance is off to one side you’ll have a fair chance of pulling a back muscle, injuring a hip joint, or damaging your knees. The rest of the pack should be organized according to your needs. Definitely consider where to put the things you may need at a moment’s notice. Your rain jacket should be accessible, as should a quart of water, sunglasses, multi-tool etc. Extra socks, and other non-essentials can be tucked into corners where they won’t be getting in your way. Every hunter has their own evolving sets of needs and experimentation will help you find a packing strategy that works best for your own style of hunting.
Be very smart about how you move with this much weight on your back. Knees and ankles are incredibly vulnerable, especially when moving downhill. Your body will automatically move a little slower and more deliberately. Don’t fight that. Smile at your task.