Mustn't forget to turn all superfluous electrics off to get as much battery time as possible...esp if electric flaps.
Agree in sentiment but should have about 20mins on the battery and from 4000 ft you'll be on the ground within about 5 so I'd fly the plane over faff with load sheading. Besides when you action the remainder of a Forced Landing Drill you should turn the battery off after final flap selection.