Cool, im glad i can pick out a monument from 100 metres! Its in a tidal estuary type area and as I was saying I think you could get to it from the other side if you knew how the local tides work. Worse case Id say a gps and a good stick would get you a lot of the way. There is a path up to 500m away but it started to become overgrown and I hadn't anything to break through with.
I might have another look at it see if I can get a closer look.