So this is either a crazy impractical idea (probably) or a genius one. Build a Maslow with the router turned upside down, so that the bit is facing out toward the user. The sled rides on a very smooth, flat surface, and the work piece rests on supports that hold it above the sled.
Supporting the work piece would be difficult, because you need a clear zone for the chains, and flexible materials would tend to bow in the center. Keeping the work piece perfectly parallel to the sled support would be critical. The advantage, though, is that the sled would no longer have to ride on all your previous cuts. Using this kind of setup, you could do true 3-D CNC routing.