I am new to the forum. I learned a lot from reading. When I got the fishing boat I made a deal with my wife that I would put a toilet in it. After reading the information on this website I have learned that you need to be careful about what you put in the toilet. The problem I am having is the fact that I am trying to put 10 pounds of stuff in a five pound sack. I am looking for two holding tanks that are approx 7.5 inches wide X 10.5 inches tall X 72 inches long. I have looked at several web sites including this one and cannot find anything close. I can have them custom built for about $400 a piece. I was wondering if anyone could point me in the right directon. Any help would be greatly appreciated.