Smokepole,
Can't agree more with the carrying a pack in the hills. With less hills here in the SE USA, I have to get creative. The YMCA machines work well, but can never mimic the trekking...where one trekking pole is bent, your left foot is everted/toes down and the right foot is inverted/toes up...and the left knee is 60 degrees flexed and the right knee just slid five feet on a scree field...No mountains here, but lots of thick grassy hillsides with enough incline to "go up and down" repeatedly, close to the house. It gets a bit boring, but some "live" Drive By Truckers, Lynrd Skynrd "Live from SteelTown", or "40 Licks" by the Stones helps keep the pace.
I'm doing an hour three times per week with my Eberlestock filled with doubled trash bags with 50lbs wheat seed, then mix it up with upper & lower body weights.
Any and all additional advice is welcome. Thanks!

I'll add one of my fav quotes: "Anyone who isn't confused doesn't really understand the situation"- Edward R. Murrow
OR..."You can't always get what you want, but if you try, sometimes, you'll get what you need"- Mick Jagger