Thanks for the replies. The real answer seems to be, I need to weigh (ahem) the options a bit more, and possibly try something as simple as moving from my default shoulder bag to the backpack (not a photo pack, but with large, easy to access pockets and room for a 4x5 + accessories), and hiking around with it a bit.

Alternately, I should move somewhere more scenic, where I can just take the car up into the scenery, and not worry so much about the portage issue. Not sure I'm ready to dedicate myself to documenting Illinois suburbia instead.