Get someone with a root plow to hit the area and your set. Get one of the big ones used in Forestry (they should be all over NW LA, NE TX) if you happen to know someone that has one. About 12 feet wide and pull it with a D-9 or so and your set.

BTW if your runway is a little rough with roots go to a little bit bigger tires. I went up to a 3" rubber wheel on my avistar and it taxis a lot better than the 2-1/2" foam wheels.