I have not read the whole thread (yet), but I believe that my situation is similar to yours. Here is an aerial view of my predicament:
The boat in my slip is highlighted in yellow.
You can see that I have to negotiate a long fairway, and then execute a sharp 90º turn to port to enter the slip when I come in. Exiting, I have to back while executing another 90º turn to port so that I can head up the fairway. The problems are that my vessel's propwash causes her to swing clockwise (aft to port, bow to stbd.), and that she is 35' long, and I believe that the fairway is about 45' wide.
My solution is to first cast off all lines EXCEPT the bow line. I have the person on the bow either hold the bow line, or tug on it as I am backing the boat out of the slip. This causes the bow to swing to port, and the stern to swing to starboard. I then have enough room to back her out until I am within 5' of the vessels on the other side of the fairway. I then cut the wheel HARD to port, and give her a blast of full throttle in forward.
If the bow person does not get it right, I have backed the whole fairway as a last resort.
I hope this helps!