How easy is it to drop the oil pan? If not too hard, could you drip it, drill a hole and weld in a low oil level sensor that would go off at 1 qt low while the engine is running and connect the sensor to an idiot light in the cabin? Tell her that if the light turns on and stays on (indicating that it isn't from the oil just sloshing around while driving), add 1 qt of oil brand x and weight y (to limit the amount of thinking she has to do).