Actually, it's safe for us to do this in the next consensus method after #23826 (moved).
This is implemented in my tor branch bug23826-23828 along with #23826 (moved). The corresponding torspec entry is in my torspec branch bug23826-23828, and is tracked in ticket #23898 (moved).
This code looks good to me, modulo open questions on proposal 283 [*]. After we discuss them, we should either merge this, or put it into needs_revision, depending on the outcome.