Ok success today! Everything but the toilet removed and already smells 200% better down below. I cleared the plugged vent line at the thru hull (damn spiders) and flushed the system thoroughly with fresh water and pumped out as much as possible. All the lines came off by hand, no need to cut any off. Being careful I bet I didnt spill more than an ounce of sewage. The difficult part of the project was removing the tank because it is a very tight fit through the access hole. It was necessary to remove the inlet and discharge elbows from the tank, they are threaded and just turn out. Also, the wooden tank mount had to be taken apart and slid aside to allow more room. Just required removing 5 wood screws that where easy to get to. So close! Still, I had to pry out just a little with a screwdriver. The big surprise was the vent and the drain hole plug on the back of the tank were installed wrong. Somebody, I assume the manufacturer, put the vent elbow on the bottom and the drain plug on top! Good thing there were 2 vents, the one in front did all the work while the one in back must have filled up to meet the tank sewage level all the time. See the picture..note the TANK IS TURNED UPSIDE DOWN IN THE PHOTO AND I HAVE THE ELBOW REMOVED.