I humped a Large Alice for 25 years
I am talking about the pack dude
They are good packs for what they were made for. Keep the weight between 35-50 lbs and it will be fine. The good thing about them is they can carry a lot of stuff. They sit low on the back, this is good and bad. Good because the pack does not hang up on stuff over your head, bad the weight is low. You can get a padded hip belt for them and it will help. A chest strap helps a lot also. They join the 2 shoulder straps together at your chest.
I always cut the straps that held the top flap and put a fastex closer on them. The 2 slots in the outside pockets are for Skis or snow shoes to go in. The outside pockets are great for 1 qt canteens. We always put our Poncho and 4-6 bungee cords in the middle outside pocket and maybe a pair of socks in a ziplock bag. The 3 little pockets are nice for ammo. They will hold a 30rd M16 mag. They are great for small stuff you need and you don't want to root through the whole bag for. That is another drawback as all you stuff in one area. You have to pack it the same each time. I can go through mine(Yea its packed) and I know where everything is. But I have done it for a long time. I still use mine hiking on short trips and hunting.
The inside Small pocket near your back is for a PRC-77 Radio but anything heavy should go there as its close to your back. You will need to get a water proof bag for your stuff on the inside(A large Garbage Bag works great better yet 3 of them one inside the other).
You lucked out dude, and as a Veteran I thank you for helping one. I hope you have fun on Eglin. I hated the place as that's is where you go through the last phase of Ranger School(Class 10-83). I have a few buddy's that served there in 6th RTB and they all said the hog hunting was exceptional.
Here is mine with my hiking buddy Dusty. We are in the Uwharrie NF here in NC.