Cruncher: isn't this a Guzumi? I stumbled upon these pages, but they do not reference each other...
Tamsin: You're right, Example 3 is certainly a guzumi. I'm not sure if guzumi refers to all good empty triangles or only the specific shape in Example 3, though. According to the discussion on guzumi, it may be a general term for makeshifts, but that discussion is not conclusive.