Well after poking around I discovered that finding an island that actually fits within a single embark region, much less one that could be squeezed into a reasonable embark size, is virtually impossible. Though I did have a filedump site up for such a site (supposedly), I never got to open it before my idiot roommate closed the page. It doesn't appear in my history either, so I don't know what he did. I think the ideal thing to look for if we want to fool around with an ocean is a volcanic cape in an evil ocean. I found a volcanic obsidian-layer forested cape today, with an aquifer and *NO* stone or magma above the aquifer. Fun, eh? Try breaching an aquifer in the current version with no access to mechanisms, hah! No cave-in exploit, smoothing or anything. Of course I did it with windmills, vertical axles, and a ton of good old-fashioned dwarf muscle in just over a year of playing (without neglecting the economy) but it is still a fun challenge if any of you want the map. The problem is it's Calm, so after the aquifer it's a dud map. Same with the volcanic island map I found.
Any island we embark on won't be completely contained within our embark site, so it will play just like a cape except for the lack of land-related Fun stuff. It is therefore my suggestion that when considering seaside maps, we ignore islands. I assume with a truly detailed understanding of the parameter system you could make the perfect map. But that's beyond me currently.
So, other suggestions? An orc-mod run on my aquifer volcano map is a possibility, but in my honest opinion it would be boring as heck with Calm seas. Going to amp up the evil and run a few more tries. Maybe the same seed with evil parameters altered. Will let you know.