Here's a link to Peg Hall's newer book. She is highly respected, and her book can help you through many harrowing experiences:
https://www.amazon.com/New-Get-Rid-B...=UTF8&qid=&sr=
You might also want to look at the
Plumbing forum, and check out what are called composting toilets. But then, I'm not exactly entranced by the
concept of carting around my fermenting fecal matter, so the dessication process involved would be preferable to me over the consequences of long term holding tank
maintenance,
plumbing and vent
maintenance. Peggie's book discusses those subjects thoroughly, and what I've read about holding tank remove/ and replacement here on CF--say it chills me. One interesting account was from a Nauticat 51
Refit thread by minaret. Take a peek at that, even though it's a sailboat, not a
motor vessel.
Ann