Yes, very likely a through fare.

The words you want are "waitlist for P class", and this is something an agent should be able to do for you. (It should look exactly like an IN or R class waitlist, but with "P class requested"). This would add you to the upgrade standby list at check-in, and it *should* carry a priority higher than any upgrade on the flight (as jsloan noted - behind anyone waitlisting for Z or higher, which is probably no one). If done correctly, you should have a decent chance of getting a seat in F assuming any become available at the gate.