I think we need to back up a little here. My comments about the Tamiya Hornet and Enterprise had to do with the widths of the islands - not the flight decks. Ed may be right in suggesting that their flight decks are too skinny as well; I don't remember checking that point. I do know the two Tamiya kits have different flight decks, which do indicate their different outlines at the bow.
Tamiya did make the distinction between the bridge structures. The Tamiya Hornet has a round bridge, and the Tamiya Enterprise has a block-shaped one (though both are too narrow, as are all the other island components). All three ships in the class had different bridges; the Yorktown and Enterprise originally were similar, but the forward part of the Yorktown's was a little different. (Later in the war the Enterprise went through a refit and got a round bridge that looked quite a bit like the Hornet's. The Tamiya kit, unfortunately, mixes up some details of the Enterprise's various configurations; even if the island is fattened up, it doesn't quite look like she did at any one point.)
Tamiya also missed one curious characteristic of the Enterprise's island. (To be fair, every other kit manufacturer seems to have missed it too.) The forward face of the funnel on board both her and the Yorktown featured a prominent gap, several feet wide, through which the funnel trunking was visible. On the relevant deck plan included in the "Booklet of General Plans" (available through The Floating Drydock), this space is simply marked "Void." The "gap" is hard to see in most pictures (it's usually concealed by either the funnel or the tripod mast, depending on the angle), but if you look carefully enough you can see it. (It shows clearly in several of the National Geographic shots of the Yorktown wreck.) I don't know why the funnel was built that way; perhaps the "gap" was intended simply to improve air circulation around the funnel uptakes. In any case, the Hornet didn't have it; Trumpeter and Tamiya are correct in making the forward side of the funnel of that ship smooth. But an accurate model of the Enterprise or Yorktown ought to show the "gap."
Some years ago I bought both Tamiya kits with the intention of using them to kitbash a Yorktown. It turned into quite a project, and I put it aside. (I think it's up in the attic somewhere; I may pick it up again eventually - but I say that about lots of projects.) I fattened up the island, using the Floating drydock plans as a basis, and changed the various features of it as necessary. I lost interest when I trial-fitted the island to the flight deck, and saw how many details on the latter would have to be changed as well. (The corrected island encroaches on such things as the foremost arrestor gear cables and the bomb elevator. It didn't occur to me at the time, but I suspect Ed's right: the whole flight deck is too skinny.)
I still think my original idea was a good one, though. To my knowledge the only plastic Yorktown kit so far has been the awful old 1/485 Revell one, from the sixties. That ship deserves better.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.