The opening doesn't need to be centered on the wing. It could be located forward or back. Are you trying to use the TS fence as a fence for the router as well? On many saws the two tools can share a fence, however, a router fence is different, at the least because you want above the table dust extraction, so you'd have to add some method to do that, perhaps an add-on fence with a capture and dust extraction port.
I have a 12x24 shop, and I've chosen to have a separate table and prefer it. I have adjusted its height so it also serves as an infeed table for larger pieces on the TS. I've seen some designs for a fold-out router table attached to a wall. I think one factor is how many projects you are doing. If it's an occasional small project, then the router in the wing would likely work out OK, with an occasional "doggonit" situation. But if you are spending lots of time in your shop making things, then a separate table might be a better idea.
BTW, no one says you can't use your outfeed table for routing. My outfeed table is flat, built with trusses to stay that way, so it could seve as a workable router table. Lay in a couple of T Tracks so you can mount a fence on it.
The more I do, the less I accomplish.