New Plan: If I buy a ticket on AA stock,
SEA-MIA on AS16 (not the AA codeshare) in H with MP# in segment
and AlaskaAir.com is showing MVPGold upgrades available on the flight
then on the same PNR book MIA-SDQ-MIA-ORD-SEA on AA with AA# in segments;
AA issues ticket
then I call Alaska Gold line and ask for YSBMH upgrade, I will get a confirmed upgrade the same day as purchase with AA?
No. I've done this exact thing (bought AS coded flight on AA ticket stock) and was told that the upgrade is only available at the airport.