One shot immediately then, if no success, wait until FL250 IMHO. Save battery; it's all you've got. Concentrate on aiming at a suitable landing site within a comfortable radius. Note I didn't say airfield. Keep your options open. Having just seen a documentary about the Bonneville Flats I might choose that over any airfield. Biggest multi directional runway in the world. I'd hope not to need the fire trucks, but walk away from it.