B Axis homing

I'm in the planning stage for the limit switches and homing sequence for my ZBCW four axis machine. The Z, C and W axes seem straight forward but B is causing me to scratch my head. The problem is that the B travel is +/-60 degrees from a vertical home position. I cannot use one of the end points as home because the X position cannot be homed unless B is vertical and if X is unknown then sending B to an endpoint may cause it to crash.
I still need limit switches at +/-60 degrees for safety so I can't turn them off.
I could possibly have a +/- signal to show which side I'm on.
Any suggestions?

Home at approximate "0" with a long cam covering 60 degrees of your travel one side or the other from 0. If you are off the home switch, travel + to home. If on the switch, travel - to clear and home at first marker pulse. A standard home sequence should work.

I like that solution. I'll use a precision optical switch and a custom encoder disk as the 'cam'.
Thank you.