Mine is 54" at the widest. I didn't put the deck any higher than the original bench seats. I have had the girlfriend, the 65lb. dog and me in the boat and didn't have any problems standing in it. As with any small boat you just have to be careful. I haven't used the seat extension yet so I can’t comment on it but I don't think there would be a problem. Almost all the foam that was built into the original benches is now under my floor as well as the 3 gallon gas tank which is built into the middle bench. I kept everything as low as I could. The decking is 15/32 plywood over aluminum framing. The boat sat in the garage for a week or two till I got the idea of what I wanted to do with it straight in my head. It then took me like five or six hours a day over like about five days (one day a weekend) to do what I needed to do to make the conversion. Never played with aluminum or rivets, have always been a wood and nail guy. It was easy to do. It is still light enough for me to remove the boat from the trailer to be able to work on by myself. Sold the little Johnson for a little less than I paid for it over 20 years ago. Right now it's cold here in Az. and I haven't had the new motor in the water yet. About the seats, if you sat on one of those square throw cushions, you sat about at the height of my seats now. #-o Usually if I stand in the boat, I stand on the floor not the elevated portions and the floor is only inches above the hull of the boat at most.