I, too, think you may be going in the wrong direction. "Ten Minutes Ago" strikes me as more up tempo, waltz or no. "A Weekend in the Country" is also a waltz, but nobody's going to call it a ballad. "Falling in Love with Love" is another waltz that is clearly up tempo in BOYS FROM SYRACUSE. Compare "Goodnight My Someone" with "76 Trombones": one is a ballad, the other up tempo, BUT they are otherwise the same song.
Maybe what you really need is a true slow song.