First of all I would like to thank all the members who helped build this system!
The complete "evolution" can be found in this post:Development of the MFT Precision Saw & Router Fence
but since the post got pretty long here's the result and a short summary.
I decided to get the 25" INCRA LS Positioner Incremental Positioning System (INCRA #LS25SYS), because with my setup you have almost 80 mm of workpiece lenght. With slight adjustments (putting the Festool Rail on the other side you could gain the width of the Guide Rail). If you have two MFTs connected the width increases acordingly! You don't need to even think about the INCRA Saw Fence, the LS25SYS is 100% square and rigid, even at full lenght
Here's the final setup with the Kapex Crown Molding Extension as support and two bench dogs.If you spend a little effort on squaring the base with the Positioner it's dead on square to the MFT grid and can easily be switched from one side to the other!
Saw Fence with almost 80 mm cut width:
Kapex Crown Molding as support (bolted with the LS base)
Adjustable bench dog (from Ebay US)
I've already built a router table to fit the MFT hight as an extension, but now it's the perfect match for the LS. The feet are adjustable and if your floor isn't 100 % I'd recommend to do the same. Takes only a minute to level with the MFT Surface. It's pretty rigid that way, but I am still working on a simple solution for connecting the router table and the MFT other than using a clamp.
Here it's connected to the left side:
And here to the front, but the beauty is you can put it on all 4 sides:
When not in use and since there's no fence in the way the router table can be used for the Kapex and the KA-UG extension can rest on the MFT and be 100% level.
I don't know if the Festool MFT Extension and the CMS Module would top this setup, but if I would exchange my top to the INCRA router table top with lift, it would probaly be pretty precise. Of course the Festool routers don't fit the Woodpecker or INCRA lifts, but maybe it's even better to use a different model for under the table anyway. For now I'am fine with adjusting the router hight by hand and the price for both the Festool Lift or INCRA/Woodpecker seems to high.
If you have any questions please feel free to ask and thanks again to all the helpfull posts!