Well.... Looks as if you will be safe from crushing. The flexion stress from the weight of the plane should assist on the score and Whack method. If you cracked your first one then you should have material around for experimenting. Take a curved piece, place it curve down just as it would be in the hypothetical emergency, place a 2/4 with a bunch or weight on it accross the upturned edges, then reach in, score it and give it a whack. Protect yourself from the colapse as this experiment doesnt have the roll-bars. Let us know about your success.