Hi ST,

1) Advertise your flight details here to see if someone will be on the same flight as you and they might be willing to upgrade you since there is no loss on their part (you have the u/g for yourself).

2) You could go into the lounge, but not sure how status members (you can identify by their luggage tags) would take to some stranger asking them...

Of course, your u/g still isn't guaranteed at the gate... only if their is availability. If it's a North American upgrade then an Elite or Prestige can u/g you, and if it's a SWU any status can u/g you, and SSWU E and SE can u/g you.
Also, if you find someone here to u/g you, they would most likely be able to get you into the lounge, saving you the pass for another time, when you're by your lonesome self
Good luck ^