I worked this out this afternoon and evening.
I decided to shoot for the moon and at least give a nod towards equal length pipes and mount the muffler on the left side.
From underneath, on left side:With the merge collector on it:
The whole thing from the left side:
Had to pop out a little to make that turn back under the bike without rubbing on the frame.
Here's the view from the right side of the bike. Just need to make up that last couple of bends. Slightly down then about 70 degrees over.
This is pretty much the only way I could figure out how to get the merge collector in there without mounting on the side of the bike. That would put my muffler much farther back than I want it, probably going past the end of the rear tire.
I'm concerned about the hanging weight of the merge collector and am thinking about supporting it under the bike. The muffler hanger will probably address this though. Holding the muffler properly ought to take the pressure off the rest of the piping if I get it just right. I don't want this thing to shake apart and crack up near the engine.
I also took time to make the final curve cut on the right side of my tail.
Oh, and here's a shot of my muffler.