I bought a V-max weight vest this year to use as part of my training regimen. Although it does not replace training with a backpack, it certainly much easier to use and less combersome. It has 2.5 lbs coated metal ingots that slide in individual sleeves to adjust weight. The total max weight is 50 lbs.

Anybody doing regular training for the mountains may want to consider one. I found mine on e-bay.

My training Regimen involves going to work every day and avoiding the the TV, especially the one with the remote, religiously. Then, for some variety, I'll fix fence or cut some firewood
Grizz