Longboard fin setup

Hi, New to the forum. I have a 9'0 that I plan on surfing mostly as a single fin, but it has a 2+1 option that I might use during the winter when the US east coast surf gets a little bigger. I really like the greenough 4A. If I got a 9"', could I use this not only as a single fin, but also as a 2+1? If so, how big should the side bites be? Looking to save $ & not have to buy a couple of center fins. Thanks! Jeff