@ SHJ - We were on this bit of waste ground, so judge the distance for yourself:
There was a rough track leading from the side of the A1101 which was just wide enough to walk (or get a motorcycle) down. The Yanks weren't particularly happy with people being there, but nothing they could do about it! IIRC we managed to claim a spot on a large pile of sand/gravel, which got our view above the top of the fence. There was nowhere else one could park a car nearby, and we didn't get caught up in long queues when it was time to head home. Looking on Google Street View it appears the trees have since grown considerably, so I doubt this spot would be much good now.
I can vaguely (I was only about 8) remember Lightnings doing something similar at Coltishall, back in the early 60's, when the base had airshows of their own. They did the legendary pull-up into a vertical climb, and (probably) went supersonic in the process - I do remember they were LOUD...