If you will email me, I will send you pix of the router system which I made. While it was Primarily a test bed, It also does work as a router. I have used some novel (I think) ideas in the construction.
As you are probably aware, the force required in plasma cutting is only frictional drag + mass x acceleration. For routing you will have to add the router cutting resistance. A higher HP router will need considerable additional force, plus introducing vibration and deflections of your structure.
Jack C. jccinc-at-owc-dot-net