Man, if your that close to buddy in front of you that you can't stop before you see any problem ahead, then your too close. You won't fall behind if you stay 15-20 feet away from the guy in front of you. If your driving during dusty dry season, I can't see why anyone would want to be to close anyways. You'd be just eating nothing but dust. I've been there many times and I try and stay way behind in this case. If I notice that someones tail gating me, I'll let them know to back off a bit. Its just not smart or safe to drive like that, especially when you know that theres so many things that can go wrong out on the trail. Ride defensively, not like a bozo who thinks nothing can hurt them. You'll be doing yourself and everyone with you a favour..