I have loads of Island addons but none are quite right.
Could you briefly list the ones you've already decided against?
I have an island i cannot find a link for (it is on my HD called Saint David this is a nogova sized island with nice towns and no river).
Saint David Island by Bloody Days Mod.
I reckon we could do with a few more specifications, to help you narrow it down:
I assume you want it to be green with woods; rather than desert.
Nogova is 10km by 10km IIRC. You want a that sized blob (or two), no intricate peninsulae?
Two airports, eh? I thought it was possible for AI to land at only one airport on each map (might be wrong though). Hope that doesn't matter, or you can script something.
Does it need a coastline, or would one of those solid landmasses do? Do you have any need for a port?
If there's going to be fighting just about anywhere, I assume you want only small scattered villages rather than big, urban centres - to stop units getting stuck.
If AI has to wander about at random, you'd presumably prefer low, rolling hills to full-on mountain ranges.
Do you want the look of any particular era? Not WWII I suppose, but latter half of the 20th century or early 21st?