sol-see
fa-fee

would work just fine, it's just that so far I haven't heard anybody actually sing 'em that way. But my experience of Sacred Harp is very skimpy (total of three singings, two of those in Seattle), so I wouldn't deny there may be singing schools out there that do it up right. But at the singing I went to in Birmingham about 3 weeks ago this coming Monday, at which there were dozens of very experienced SH singers, I didn't hear any articulated accidental syllables.

Haruo