Realistically though, permission for anything invasive in the WHS isn't going to be easy is it, not until the establishment got convinced it really was something.
Ideally, if it was cleared of the trees and scrub it would be good as it would stand out better, and a non-invasive surface survey might show something about it's shape.
I have this suspicion that it has a number of Silbury-like distinct facets rather than just being round, though that could be wishful thinking - anyone else noticed?
How could we prove it, as amateurs? Steve - any suggestions? My thought was that if we put a tall pole on top with a fixed length of string and then walked round on the slope of the mound holding the string taught and placed marker sticks..... or something?