Here is a clinker hull based on a N12 but with a Yawl rig and Lugsail main
http://www.ebay.co.uk/itm/sailing-dinghy-/221038782709?pt=UK_Sporting_Goods_Sailing_Boats_ET&hash=item3376f028f5
ah ha one should not confuse a national 12 with an international 12 a very differnt beast although i don't think they allow twin masted riggs either!
Ahh - never new that was a class - knowledge updated! - anyway, the point still stands, and I bet she sails beautifully (for cruising)