If you still haven't had luck and are at the airport. Check the upgrade waitlist... if F isn't checked in full yet politely ask the GA if he/she would be able to move you into an aisle seat should one come availble after upgrades are processed. If you are polite, mindful of how busy the GA is, and stay within range of the GA's eyesight, it's likely that they'll remember you and swap your seat should one open up.

I've done this in the past with E- to E+ and it has worked. The times it hasn't worked was when the flight was heavily oversold and/or I didn't stay within range of the GA's eyesight.