Hmm, do purchased preferred seats yield MQDs on award tickets?
Crazy idea: leave your wife's FF # off the upcoming reservation, and buy a preferred seat. Then claim retroactive mileage credit. Preferred seat fees do count as MQDs, at least on revenue tickets. No idea whether this will work, but it seems plausible.
More sane/sure idea: just book the cheapest same-day turn out of your home city.