Easily the best way is to use a video recorder. Switch it on, set to "record" and lash it to a suitable halyard and send it up there. It would be useful to have a second line attached to the video recorder to sort of move about a bit. But with any luck the resulting video will gave a nice up-close video of the masthead. Alright, with a lot of luck.
Going alongside a tall bridge, after calculating the tidal height from a secondary port, which is, however, less fun than a mate with a radio controlled helicopter.
google earth would only show it right on top of the mast tho, and a bit fuzzy. Also probably the condition last season.
Another method would be to use tried and tested "careening". This involves somehow getting a rope around the mast and winching the boat over until the mast snaps, and it will then be easy to check on the masthead.
I wonder which or is it what astral plane you lot are on. Some great ideas though I particularly like the careening one must check with the insurers seems a good way of getting a new mast and rigging on the cheap thereby negating the necessity of inspection and maintenance.
I've had disappointing results I'm afraid. I've done it myself, when "on the plane" (ie. on the "astral plane", which is what I think you mean by "astral projection"). My boat is moored some distance away from where I live so it's very convenient to be able to go "on the plane" when I sleep, and check up on the boat.
Unfortunately, it's too dark to see anything clearly.