Bob Keen is almost larger than life--big in stature, a self-made millionaire, already part of the legend of the northwest. His fortunes began with a second-hand caterpillar tractor, bulldozing mountain roads. Now he owns oil land, operates road, water and air transport, flies a plane, drives a chuckwagon, and is listed on the stock exchange. For all that, he's a modest man who still likes yarning by a campfire with old cowpuncher pals in the big game country of the Rockies.