I just went out and measured my 228, much smaller version of your boat. Just the cockpit and the helm is 60 square feet, so I think that part would be about 85 square feet in your boat. Then there is all the rest you are doing, I'd guess somewhere around 120 total.
That said, I looked into seadek for my boat, didn't do it because they set my expectations at about $2K for a pretty similar setup to your picture, came and measured and said almost $6K. I said hell no.
As I've learned more, I'm glad I passed. Yeah, the seadek (or whatever) looks really nice when it is brand new, but if your boat is a fishing machine like mine, it will quickly get covered in fish blood and guts and it doesn't clean up anywhere as "easily" as the naked boat does.
If your boat is a party cruiser, wine and cheese, no real dirt sources, then by all means, seadek would look fantastic. Just not for a fishing boat until you've tried to clean it.