Not sure if it's an option for you or not, but practicing for the real thing is your best bet. I do a backpack trip every weekend thru the summer so I can carry the same year I'd Cary on a hunt. It also allows me to test different gear and food so that when Sept. hits I'm already dialed in.
Seems like a lot of guys get these to cure PF. But, what about guys that don't that. My feet just get super sore after about 5 miles with a heavy pack, do these help with that issue?