Yeah so I ended up pulling all the internal adjustable supports, and only needed one 'strut' to position a 40D with a 200mm lens. A small spot for my 50mm was easily partitioned and loading my monopod (externally) opposite the camera body provided a measure of safety and counter balance to my slightly shifted load.
I used the extra dividers to provide more padding wherever the camera bits touch the wall of the pouch.
When I first set out on my beach cruiser I thought the load was a bit much, after all I'm used to both shoulder straps spreading the load, and a slightly larger waist band on my Oakley backpack (vintage 1996).
I tried to get more load on the hips but with the narrow waist straps but this created pinch points. The way the adjustable part of the shoulder strap dug into my chest was and remains a concern, even with a thick cotton hoody on.
By the time I got back home I was a bit more acclimated to the pack, but I think I will have to strongly consider another solution with both straps.
EDIT: I really like the smallish size of the Tarmac Velocity 8, so I went back to REI and added a
woman's hip belt, which stuffed with much effort into the strap stash pouch of the tarmac bag! This really puts the load on the hips where I want it. Of course I'm $115 bucks into by now, but it is a custom creature of my own creation and that is satisfying.
-Shea