Ended up getting one of these:

http://www.lowealpine.com/eng/prod_app_det.php?catid=11&itemid=324&type=man

Its the same size as my Osprey Atmos bag, but twice the capacity. (The ospreys ventilated back is stupidly overdone limiting storage space). I can actually fit my bigger Lowepro bag in the bottom of the Lowe Alpine bag and open it through a front/side entry panel which is handy, though impractical for actual field use. I think I will find a smaller bag that fit hold the camera + 1 lens which will be lighter and less bulky sometime.