Mex,
I guess BFL got inside my head, cuz when I woke up, I was thinking about the stacking issue. So I decided to stop screwing around, and look at bus bars. Well, now I see you also mentioned bus bars. So, I'm going with a couple of these:
http://www.ebay.ca/itm/BRAND-NEW-Blue-Sea-2127-Maxibus-4-x-5-16-18-Stud-Common-/331033970255The only stacking will be a single thin terminal ring (for light gauge wiring), on top of a heavy duty ring for the chargers, inverter, and such. And I can leave the shunt as is.