Whistling Rufus has long been a "group number" at the ABF rallies, played all together in the round robins, as well as informal jamming.
WF has been a subject here in the past, mostly regarding the CE publications redaction or oversight of the final strain.
Many, including myself, play an arrangement (more or less) that was written out by the late Elias Kaufman. I also presume that some just "play by ear" as the piece is not that difficult.
Here is the "official" banjo arrangement from J. A. Mills (being the original publisher).
As a banjo solo, it is a bit anemic, but there are some places that are different than how it is generally played. The trio follows the "bass solo" format. I might incorporate some bits of this into my playing of it.
This is complete with 1st, 2nd, and piano (though in A notation).
https://archive.org/details/whistling-rufus-a-notation-kerry-mills/...