If you don't absolutely need ports, don't put them in. This is a last resort to make repairs or access the inside of the hull. The strength of the material (deck) that you remove is never the same when you replace it with a port. If you have to put a port on the deck, you're picking the better location behind the front crossbar. The deck in front of the beam can be put into compression when the hull flexes, and especially closer to the crossbeam.