"Your discretion" generally solves most problems at that juncture.
Popham do this, it works fine. "readability 5, QNH is nnnn, taxi at your discretion", "line up and take-off at your discretion". No impression of a clearance, but communication flow is maintained and everybody is happy.
(At-least Popham used to do that, I haven't been a club member there for a few years, more's the pity - great club. I'm only guessing that they still do it that way.)
G