I agree w/ ben's recommendation- you have a nice light base weight, give some of the lighter framed packs a go first- if they don't work out you can send them back (if still in resalable condition) or sell them here where you can recoup most of your $- then move to the heavier packs if need be

would be a shame if one of the lighter framed ones would do the trick and you never get a chance to try them

Another thanks to everyone, I will take it all in. I still have a god bit of day hiking to do before I have to make a decision. I'll do some more trying on and research the McHale and ULA.

Wow, 7.5 lbs isn't very much. How would you even be able to tell the weight was on your hips and not on your back? Perhaps you could make your own pack that is like a giant fanny pack. I still have an old Jandd fanny pack that was supposed to go with a harness system that would keep the pack from bouncing too much. It's not big enough to carry sleeping bags and everything, but maybe a similar system could be created.

...in my lower back so I can sympathize with the OP. I've tried several packs without much success. I do have a McHale pack and I stripped it down to achieve the lightest weight possible. Get the weight on my hips.

It didn't work for me which is why I'm now going to the other extreme. My back was least effected when I wore what was essentially a large summit stuff bag. No pockets, no frills and all weight carried by my shoulders and upper back.

I'm going back to that approach and getting the lightest pack I can get my hands on, a ZPacks. Maybe it will work, maybe it won't. The back is a finicky thing and, sometimes, it's the strangest movement, such as a twist one way or the other, that will throw it out.

The OP is doing the polar opposite of me. I hope it works out for both of us.

Fred,

My hiking partner had a lumbar discectomy last year and went through this same search. He settled on a Natural Balance from Aarn packs. He said it is able to transfer almost all the weight to his hips, and has the added benefit of balancing the weight between front and back so as to eliminate the forward lean required with most backpacks. I tried it on one of our trips and was pretty impressed with it- enough so that I am probably going to get a Featherlite Freedom for myself. That is the model that I would suggest you look at. Even though it is probably a little large for a 7.5# base weight, their smaller packs appear to have smaller and less effective hip belts. Featherlite Freedom

Good luck in your search.

I use a Aarn Marathon Magic 33 and carry about 22 pounds. All the weight is on my hips and the balance ft to rear is also very good. It is the most comfortable pack I have tried.

http://www.nielsenbrownoutdoors.com/2010/03/aarn-marathon-magic-33.html

If you are interested in an External, check out the LuxuryLite packs. The regular pack with 3 cylinders weighs about 36 ounces; they do have a version that uses Cuben Fiber for the cylinders. It weighs 1 1/2 pounds. The pack transfers ALL the weight to your hips. Not sure if it would meet your needs, but I might be worth checking out.
Web address is: www.luxurylite.com

I too have a couple bad disks but no bone fusion, as of yet. I use a modified GosamerGear Miniposa with a hip belt and large sized waste pockets. This keeps most weight low and fairly well balanced. Near as I can tell, about 5 pounds on my shoulders out of 17 total pack weight. I am also about your age. Just my ha'penny's worth...
jdm