My boat is a 235XLC. I am 5' 6-1/2". The horizontal dimensions are pretty good for me. A reasonable amount of room to stretch out with room to spare. Vertical measurements are a different story. When laying down in the forward area of the cuddy [bow], you can't sit up. You kinda have to crawl/slide to get to the steps leading out on to the deck. At your 6' 4" height, you'll probably fit ok but not much room to spare. And if you're going to take a porta potty with you....well, hope you can bend over! haha
But then I take into account you're looking at a 215ssi. I've never seen one in person, but looking at some images, I don't think it's gonna be a good fit for you guys. especially if you're both going to overnight somewhere. But if you're only going to use the cuddy for storage, that would work.
Before you buy that boat, make sure you and your wife both try the cuddy together.
