There are a few folks working on triples. Most triple projects "evolve/ are an offspring" from a double visual -- Lavender Pied or Caramel Glow for instance. It is at that point a third gene would be mixed in the from a visual or Het.

Some breeders are starting with triple Hets. The Sloan's are working the G-Stripe Hypo Caramel. In my opinion, to do a triple project WELL you should be prepared to hold back 50+ offspring.