Just a thought... I haven't heard of this, though.
MS will (or historically has allowed) a one-time exception to your banking deadline, and allow you to bank points after your deadline has past. Note this is supposedly one-time-only thing. I used it myself this past April (actually on May 1).
I wonder if they would allow a similar one-time-only exception going the other way, and allow you to "un-bank" points back to their original UY.