wait like a week until after the 'official viewing' time and then backcountry camping higher up.
The idea that they are only in the small area around Elkmont Campground is another of those things the park says to discourage people from seeing them elsewhere and to minimize the impact of the masses. What I have always done to bypass the whole stupid bus line from sugarlands is to just pay $20 for a campsite at Elkmont for the night I wanted to go. (which by the way used to get 2 cars in per campsite) Then we could grill burgers relax, fish whatever until it go dark, then hop in the car and leave without dealing with the lines. It's probably too late to do that now, the campground fills up way in advance. Now I avoid the whole thing altogether.