Wood? That rather precludes adding a backing sheet so you can use use a vinyl cutter with ink jet. You are now have a flat bed table with either 3 heads or interchangeable. The set width and heads requirement sounds like a bespoke machine.

I think you need an engineer. If I was still young and hungry I'd draw up the table as a kit of parts for laser cutting (needs tube and sheet cutting lasers), estimate the price, double it so I could remake the whole she-bang when I understood the problem and relieve you of the money

Some thoughts.

If you want to do wood you will need dust extraction.

Make sure it will do the max length you may ever require in the future. Be generous.

When you cut this sheet with a knife, could you do it one handed or would it slide about everywhere? If it slides you will need a vacuum or electrostatic hold down.

Pen plotting text is dismally slow (especially if you add the inertia of a router head) and you will probably want a soft landing for the pen.

Are you really sure this is the way to go? Beware enthusiam :naughty:

Good luck

Robin