To get the extra Z, it seems like the challenge is one of keeping the whole system rigid. Seems like the side rails on the CAD-CUT could be higher and then the Z is larger. Sorta, "don't raise the gantry/bridge - lower the work surface."
Thats the approach I plan on for getting extra Z in System2. Its not yet 5x9 (to cut a 4x8), but I'm thinking of going to rack and pinion drive when I move up to that size.
Like the car bits idea - I'm on the same path eventually as well as boat bits.
Jim