Best strategy if R space appears within 24 hours?

I don't know if this should belong to any particular thread. If so, mods please feel free to merge this into the thread.

Nowadays it becomes more and more common that R space would only be opened within 24 hours of the flight. I've thinked of the following strategies:

1. Do not apply RPU/GPU. When R space shows up within 24 hours, call UA to apply them manually.
2. Apply RPU/GPU 24+ hours ahead online but do not check in. When R space opens, call UA to upgrade into R manually.
3. Apply RPU/GPU 24+ hours ahead online and check in. When R space opens, call UA to upgrade into R manully.
4. Apply RPU/GPU 24+ hours ahead online and check in. At the airport, find an agent to upgrade into R manully.
5. Apply RPU/GPU 24+ hours ahead online and check in. At the airport, do the battle field fight.

I've successfully used #3 a few times, although most of the time the phone agent just pushed me to use #5. Is #1/#2/#4 possible? Has anyone used #1/#2/#4 and succeeded?

Also, it is very frustrating that sometimes after I check in, I am NOT on the upgrade waiting list anymore!:mad: I have to find an airport agent to put me manually on the upgrade waiting list first. But most of them don't know how to do it correctly and put me in the same category with those using CPU.:confused: Is that common? What can I to do avoid such situations to happen again?

Thank you for your inputs.