I have a 52" rail set on my TS fence and therefore a large extension board to the right side of the blade. I have mounted my router there. A few comments on this type of setup.
1. I would not like to have one fence system for both TS and router. Setups take a lot of time to create, and as I work on projects I have needed my TS and not wanted to break down my router setup to use the rip fence. That may be the haphazard way I work, but I expect that over time you will find the same thing. The reproducibility of the Incra system will however be a distinct advantage here, although I expect it will take more than a few seconds to reproduce the setups.
2. Here's how I work on the router table. The fence of the router table is to the left of the bit (looking from the front of the TS) and between the router bit and the TS blade. This means I use the router table feeding material from the back of the TS extension table towards the front of the TS. Placement of the router insert is key. I like having a reasonable working space between the right end of the extension table (which in essence becomes the front of the router setup) and the router bit, but I do not want to have to bend over to reach that. You have to find that happy medium: enough space but not reaching.
3. While any setup is a compromise, I like this better than a free standing router table in my already congested shop (congested in part because of my 52" rails on my TS). It not a perfect setup (the router table has some sag), but it works for me and I live with it. One other disadvantage is that clamping router fences is not particularly easy due to the uneven and somewhat haphazard support system I have for that big TS extension board.
I hope this helps your thinking on this.
Henry W