OOMB- Read the thread and the title rang a bell. Found the song on Kate Lissaeur's CD - "Ain't no Grave", but played on fiddle, not banjo.
Sat down tonight playing with different tunings, and am coming near to SOMETHING which fits the overall "feel" of the tune.
If I find time to get further on with it before you find what you want, I'll show you my take on the tune! So far the best banjo tuning seems to be :-

D
B-flat
G
D
.   G

Quack!
Geoff.