I think i2i was saying put the ballnuts on the ends of the axes, instead of near the middle. That way, assuming you have room for the 16mm screw under each, you would just need to use a longer ballscrew to get the same travel. It's actually rather like how I mounted it on my lathe cross slide. There I extended the saddle with a milled block of steel, then mounted the ballnut to that to get it outside. I also had to mill a fair bit from the bed to fit the RM1204 ballscrew in.

Edit: Didn't see post #13 before submitting this.