I could only see where it started fromm at BC. I would say it starts right where the letter "B" in the word Club is. Just above the F - which denotes where the store is.
I really don't think the walk to SAB will be all that bad. Yes you may have to walk through the BC, but if you go behind the elevators you may not have to walk though the main lobby area.
Personally, I like walking through that lobby. This week after staying at AKL, I really enjoyed coming "home" to BC when we went to Cape May Cafe one morning, we parked in the parking lot at BC and then went to Epcot for awhile (don't tell anyone), later that day when we came back we just walked through the lobby to the parking lot, I really enjoyed the smell when I walked in kind of like a clean, bleachy, clorine smell (I know I am strange). I just had a hard time with the smells of the cooking at Bomas when you walked in AKL.