Re: upper sun deck
This is certainly not something you can just do, it will take alot of engineering to get it to where it actually works and doesn't tear the boat up, there si alot of weight involved and you have to plan for it to take whatever your top speed is.
I have never seen a kit for this, we bulit them for several years at Bennington but dropped that option 2-3 years ago, also keep inmind with that much weight high it makes the boat react alot more to wake, they really get to rocking.