I would try a bow eye with a strong back-up plate. Most people who
moor their E27s in slips use carabiner-type clips attached to the
stem fitting which is plenty strong.
Or perhaps a bridle could be attached with clevises to the toe rail
on both sides. The toe rail is plenty strong and through-bolted
through solid glass. The bridle could be detached for sailing.
However, as I type, it occurs to me that the toe rail is aluminum and
might wear quite a bit with the boat on a mooring. ??? Maybe somebody
else has a better idea.