I am trying to install a holding tank on a 1984 traditional interior boat. This boat came from the factory with an installed head but no tank. I bought the riggh tankfrom Catalina Directbut am at a loss as to how to fit it in the port sette. Under the cushion are two holes covered with removable wood as on other openings, and there seems to be no way this tank will fit in them. If anyone has done this project please help me. I sure hope that it does not involve serious cutting. Thank you for any info.