I was thinking of moving the plate which currently carries the motor even further in, so that it is virtually rubbing(but not quite!) along the belt.
This would mean a sub-assembly to carry the motor itself, but I was thinking of the tracking of the belt as the main problem, rather than the number of parts.
As to mounting the whole assembly, I suppose the first decision is which moves, gantry or work.
I, too, am going through the "how big do I need" rather than "how big to I want" or even "how much room have I got".
My current machine, still the Mark 1, though rebuilt many times, has a cutting area of 16" x 30" on a 22" x 36" bed, and this can just accommodate the dulcimers I'm now trying to make.
That's OK if I rip up the 8x4 ply into the sizes I need, but then have to do several operations to trim, and then clean up afterwards.
With an 8x4 + bed, I could think in terms of a single operation, drilling, milling and cutting out all part of a single programme.
If I did go to this size, I'd be forced to stick with a moving gantry, but if I stick to the sort of programme I'm following at the moment, cut and laminate the parts, then drill and mill, I would definitely go towards a moving table.
Sorry it was such a ramble, but that's me