imo the foam pit seems like too much maintenance, impossible to keep weather out without complicated drainage system, foam would go bad and need to be replaced too quickly, pit would need to be too deep and have expensive shoring to keep from caving in, etc, etc,
i think the airbag wouldnt need a big excavation or be below ground necessarily, but would maybe require drop in/kicker to be elevated a little higher. above ground would seem to eliminate a lot of issues that come with the "pit" construction. airbags are pretty expensive though.
he owns the land, has no hoa restiction, basically can do what he wants (as far as we know). it seems like a long shot but i was wondering if anyone had experience with this? i'd post in build-a-jib but thought this would get more traffic.
he's a snowboarder so if any or all the ideas seem borderline retarded thats why.
also if anyone has a hookup for used airbag lemme know