As a plat you'll earn about 60k total miles on AA. Which would be enough for a F mileage saaver award. Do you value the status on United more than a $4k-10k F class seat?

Also, are you 100% sure that you cannot get another 15k miles? I priced 4 weekend trips (late friday - sunday) during the summer to central america and to some nice islands for $1,450. I'm sure that you could do better with fall/winter dates and costco gift cards.