We are interested in outfitting our sirius for cruising which may require the addition of some water tanks, lines and perhaps a fuel line. We understand that there are 3 main flotation compartments, one under the V-berth and the others under the quarter berth area on each side. Has anyone opened up any of these areas to know what is actually in there? Blocks of foam, injected foam, or is there any room to work inside these areas to route lines, etc??