NOTE: A similar thread was posted this summer in the G-Spot forum. It really has more relevance here in the winter forum.
I've searched for a few years for the "ideal" backcountry ski pack and finally found it - well, almost.
I got a Camelback "Commander" camo hunting pack but had to modify it to make it into a good touring pack.
So I cut off the unsupportive cloth belt and used an REI Ridgeline belt. As you can see, it fit perfectly behind the pack's lumbar pad (after I unstitched & bar-tacked it). Again, luckily, the pack's side belt web strap exactly fit the REI belt's buckle for the same purpose.
Then I added 1" wide aluminum bar stays to support the wimpy plastic frame sheet. As you see, I covered the bar stays with black (Gorilla) duct tape to protect the pack's fabric from wear.
I bolted the frame with 4 stainless steel bolts, washers and Nyloc nuts. The frame is 3 pieces, 2 vertical stays and a top crosspiece. It's inside the zippered water bladder compartment. I used a red hot spike to VERY carefully melt the bolt holes in the pack fabric.
Next I cut through and removed the bottom ladder buckles on the side compression/ski straps and replaced them with quick release buckles. I slotted the new buckles W/ a diagonal slit (Dremel tool) to thread them thru the webbing. This saved unstitching & re-stitching the webbing.
You can see that it permits fast removal & attatchment of the optional REI side pockets.
Finally I added bottom straps and buckles to hold a Thermarest Trail Pro winter mattress and any other necessary gear that wouldn't fit inside.
mattress if I felt there was a distinct possibility of an overnight stay.
This pack already had the following:
1.external shovel pocket for my avy shovel
2. protected hydration bladder tube (in the shoulder strap)to keep it warmer
3. internal Velcro straps to hold my avy probe and snow saw vertically
4. side ski/compression/pocket straps
5. the 2,000 + cu. in. volume that I wanted. The side pockets add another 800 cu. in. If I need even MORE room I have huge Dana Cordura side pockets as well. :)
Now, with the belt and stays,it can support a "day-and-a-half" load if necessary and still keep the load well under control. With these mods I now have what I feel is my "ideal" winter BC pack.
P.S. All the sewing was done by a very understanding and skilled local shoe repair shop.