I learnt to play the banjo many years ago mainly by picking out tunes with my thumb. Once I knew a few cords, I still used the thumd to hold the tune and my first finger to play the cord. Sounds a bit awkward, but thats the way I play. I use an old time style Gold Tone to accompany singing and a Vega/Martin bluegrass (set up to sound a bit more mellow than usual) in the band.
I also taught my wife to play this style, and she is now a pretty good player, although she is also able to use a couple more fingers.
Good luck whatever style you play - just keep pickin'