I had serious nerve damage inflicted on me by an Alice pack and it's narrow waist "pad". I went down to the PX and bought a civvie waist belt for a frame pack and had the riggers sew it to the Alice pad - worked for me.
My best ruck for for "heavy" missions was a 1944 back board (the molded plywood one) my father brought back from the "big one". I added a waist belt to it, but it was otherwise stock - you could strap ANYTHING to it, and it worked better for those 80-pound commo-guy loads than anything else I tried. The riggers had a cow the first time I went to jump it, but it was still in the manual (with an 81 baseplate strapped on) so they had to let me go.
