Try again on the day of flight.

I've had this happen twice (SFO-somewhere in Europe, and FRA-SFO).

Both times I was able to waitlist at the airport. One cleared at the gate, the other didn't but I was #1 or #2 on the list.

At the moment your status means nothing as the waitlist is full, but on the day your status still counts so you'll be able to trump most of the rest of the people on the waitlist who are lower status.