Natures Head composting head on Brigadoon.
No holding tank, Y-valve or hoses to have to replace. No head to repair.
Simple, effective and easy.
Looks like a good plan. How does ease of use compare to that of a porta-potti? Where does it vent?
BTW, I wouldn't be opposed at all to buying a boat without any head at all and just putting one in from scratch. Much better than inheriting an abused and poorly designed system and having to remove it later.