Pete
Sounds like an indifferent caddie issue to me.
With something like a rock on a hill, it's a reference point. I wouldn't expect the staff to move the rock around to correspond with tee markers. Players would need to know where the green was relative to the rock. Besides, with multiple tees, do you have multiple rocks?
I only played Prestwick for the first time last year. No rock - they now have boards painted to correspond with the tee one is hitting from. If the tee moves around, then you still have to mentally adjust the line. Or your caddie would be expected to. The staff does give you an indication of hole position (note the simple solution on the tee box).
DSC00040 by
john mayhugh, on Flickr
DSC00042 by
john mayhugh, on Flickr
Worth dealing with a blind shot to crest the hill and see this.
DSC00044 by
john mayhugh, on Flickr