The best thing to do is have someone photo or better yet video you sailing from the back. The big top sails are designed to twist off (depending on settings of course) but it will be very difficult to get the leach tell on the top pocket to break, and if you do you will find you are way way over trimmed. In light air you can sit forward and site up the mast to get the settings right, but as it picks up getting a good perspective on what the sail shape is doing is much more difficult.

I used to rely on a leach tell on my H16 on the second pocket down almost exclusively. The tear drop mast that did not rotate made the forward tells pretty hard to read. On the new boat I have found the opposite. Up wind I can tune the downhaul and rotation pretty easily with the forward tells and sheet to feel. Up wind I no longer look at the leach tells. I do use them for gross trim when heading down wind though.

Matt