I was considering swapping out the deck plates on my Nacra 5.0 to make them a little easier to access the hull for storing water bottles, etc. Will that compromise the integrity of the hull?
Depends on how larger you're planning to go I suppose. Standard access ports are between 4" and 6" diameter.
6" ports can be a little large for some applications but 5" is generally OK and provides plenty of room for storing most items. I guess if you wanted to go even bigger than 6" (like a rectangular port) you could add some partial bulkheads to reinforce the deck.