I'm starting winter chores on my new (to me) 77 ODay 25. For some reason the previous owners installed a holding tank but never cut in a thru deck fitting for pump out. Apparently they brought the pump out hose through the forward hatch and hand held the discharge hose from the tank while pumping out. Needless to say, I want to extend the hose and cut in a new thru deck waste fitting. I can go either to port or starboard as the tank is amidships under the Vberth. Any preferences? Next this is my first attempt at cutting the deck. I assume that I go through the deck and ceiling liner with a 2" hole saw. Then for the mounting screws, I drill through the deck and liner then come back through the liner with a larger bit in order to get the bolts to snug up to the underside of the deck rather than the liner? Sorry to be so basic but I've never done this before. What kind of caulk should I use? Thanks for any advice.