40-45L panel loading backpacks?

I am looking for a hiking backpack to use for my photography. There are photography specific hiking packs from Fstop, Shimoda, and now PGY but they are over-padded, too heavy for their size, do not breathe well on your back, and are usually 2x more expensive than the hiking packs.

However, almost all hiking packs in this range are top-loading.  Backpacks with a brain are a PITA when it comes to frequently removing and replacing photography gear – I may do this dozens of times per day on photo-specific outings.  The only things I can find that come even close are

1. Osprey Stratos 34 – a very nice pack, would have been perfect if it was 40-45L
2. Mystery Ranch Coulee 40 – perfect front tri-zip system, great size, but the harness is an older design that does not breathe very well.

Anyone know of anything else I should consider?  I have been looking for a few weeks and can’t find anything.