I have always been amazed that boaters will spend hundreds of dollars to move a "poo" three feet, in the misguided hope that they will never see it again. The one fact about boating is that it brings us into sharp contact nature, this includes beautiful sunsets and bodily waste. Unless you are prepared to pay someone a lot of money you are destined to get "up close and personal" with fecal matter at some stage.
Peggy Hall is the agreed expert on such matters and I would recommend her book without reservation;
"Getting rid of boat Odors etc."
Like Peggy, I am no fan of holding tanks having discovered that pump-out stations are rare in most locations. I was therefore interested in a the idea of a composting "head". The Airhead being one example.
The provisional plan is to install one in the for'd heads with a "Lectra Scan" dealing with the aft Heads.