Have you tried the geoweb system from Presto products? Find their info here:
http://www.alcoa.com/alcoa-geo/en/home.asp
This isn't a groundcover, but I'm not sure you're going to find a ground cover that can stand up to ATVs. You didn't include location info in your profile - go
here and fill that in with where you are - it might help others to suggest plants for you.
Otherwise, give the geoweb a try. Fill it with sand, or you might be able to get away with native loam (give them a call and ask to speak with an engineer).