Jerry, the advantage of deck plates is you can thoroughly dry and inspect your fresh water tank. No more groddies! Make sure any caulking is for portable water too.
And, once it's dry... you know you don't need to put anti-freeze in it. Right? You can disconnect the fresh water tank and using your pump... pump anti-freeze right from a jug into the plumbing system... by passing the fresh water tank AND the hot water tank (if you have one).
Ten Forward - 2014 Escape 5.0 TA
Double Yolk - 1988 16' Scamp Deluxe