I'm the same without the boob problem. I Leave that to Tess. I have a Gregory pack I take everywhere. It has a mesh back that holds the pack away from your body and doesn't completely stop but diminishes the sweat under your back pack. But it's not made for cameras, in fact ti has design functions that are anti-camera. For some reason it gets narrow in the middle making git hard to get lenses in and out. But I use it anyway. Of course it has the chest strap right across the boobs, so Tess can't wear it.
I've basically come to the conclusion that if I'm going to wear a pack I'm going to suffer. My current strategy is should straps and holster with attached lens bags. On shorter walks I take a sling bag.
Packs are a pain... that's just how it is. There is no sweaty back thing happening with this rig.
I've since replaced the "contraption" belt used to support everything, with heavy duty shoulder straps, and the K-01 has been replaced by a K-1 with DFA 28-105 and the DA*60-250 has been replaced by the DA*200 and 1.4 and 1.7 TCs, which can be stacked on a K-3.
Does that picture make me look fat?
Everything is handy, and I can walk for miles with it on.
This picture is from a few years ago... but it's still my preferred hiking set up. Everything is convenient if I need to change lenses, standing up without putting pack or anything else on the ground, especially since I've gone to shoulder straps allowing me to move the whole holster to the front of my body.