Take a look at this bit of “Very Mock Morris”, reduced to two staves and with a fifth voice added to fill the chords better. Again, it’s in BP notation, so I’ve filled in the note names which aren’t what you’d expect in the bass clef:
The intervals in the melody are wider than in standard tuning, but otherwise it looks exactly like a typical morris tune phrase ending which you’d harmonize with a V7-I:
Today I was thinking, “wait, how can that work in BP? In standard tuning the D-E-F# run starts on the root of the V7 and passes through E to the leading tone which is the mediant of the V7, but in BP D is not the root of the V3 and the leading tone is not the mediant.” So I thought I’d been trying to be too analogous to standard tuning and wrote a melody that didn’t work with the harmony. I went back and looked… and it’s fine. No, the D is not the root of the V3; but it’s the 3! And the leading tone is the mediant of the V3 (of course it is, that’s why I decided V would work as the dominant chord); it works because the wide triad is, well, wide, so the mediant is further from the root than standard chords lead you to expect.
The relationship between the melody and the dominant harmony isn’t the same as in standard tuning, but it works just fine. Or at least I think so.