Do not tie the three pins together and come out with one wire.
The R and +B pins are the regulator output and are internally jumped, so these two wires can be tied together. This typically feeds your bus through a fuse, about 30A.
The C pin is control and sense. Power to the C pin turns ON the regulator, when the C pin senses greater than 14 volts, it turns OFF the output to R and +B. If you jump the C pin to the R and +B pin, the regulator will self excite and can only be turned off by stopping the engine because the R and +B will feed the C pin until the magnets stop spinning. Opening the master switch will only disconnect your battery and cause wide voltage swings on the bus.
I would use a two pole master switch, one pole to power the master relay, the second pole connects the C pin to your bus.
