[Doug G]

Funny you should mention the pryamid structure idea. I was envisioning a similar obstacle(s) - but inverted. Going with the moon-fish hint - maybe a large elevated crater, like you see at mini-golf courses. Of course, back on topic, the drive train isn't affected unless it is a large "crater".

Also if you want to get into selling universal robot chassis that go beyond FIRST, I'd look into some all terrain options/solutions with suspension and pnuematic tires.