The fretless "capo" (if you want to call it that) is to slide the bridge back and forth. Closer to the neck gives higher tnings, closer to the tailpiece gives lower tunings. I have 2 gut string fretless Fleshers. Fretless banjo tunings from the old days fall into high bass and low bass. The high bass tuning is equivalent to a modern banjo's G tuning, and the low bass tuning is equivalent to the so-called standard C tuning. Only the bass string gets changed back & forth to go between these two tunings. My "Boucher" model is tuned in D high bass or G low bass, but with the "fretless capo", it'll do E and A also. This D is a third below a typical modern bluegrass banjo in G. My "Dandy Jim" model has a longer neck and a bigger pot and heavier strings. It is tuned in A high bass or D low bass. (That is A nearly an octave below a modern bluegrass banjo in G.) With the "fretles capo", it'll go to B and E.

Other tunings besides the traditional minstrel tunings I have mentioned would also work on a fretless banjo, same as on a fretted instrument. Again on a minstrel instrument they will be lower in pitch than on a modern instrument.

I have a lot of songs I love to play on my fretless banjos. I play "Little Mohee" and "When you and I were young, Maggie" on the "Boucher"in high bass, and "Jordan is a hard road to travel" on it in low bass. I love "My old Kentucky home" on the "Dandy Jim" in high bass, and "Arkansas traveler" and "Chicken reel" on that one in low bass. Sounds like a "Chicken reel" for "Foghorn Leghorn"!

Joe