Yes, it is a cabin top traveller. Unfortunately, the boom doesn't go that far over the cockpit. (you can see it in the picture on my profile page.) And there's a dodger that's covering the front of the cockpit, so I don't think that would be feasible, although I like the recommendation of not having to rely on a winch.
I wonder if anyone's put blocks at the mast foot and tried to route the sheet forward, then to the side and back towards the cockpit?