I have been playing around quite a bit and this is what I have found. You can set "Mesh" interval at any convenient number and it changes the size of the displayed boxes that make up the coordinate grid. I set the interval at 12 and used that as a scale foot. Using full sized plan data and the 12 inch scale of the coordinate grid, it was easy to do a somewhat scale replica.
I read about someone doing this but setting the interval at "10" because they were used to metric. My thanks to whoever that was that I read this idea from.
As Gary said in the previous post, it doesn't really change the model at all, it can be scaled after you finish. It did help me quite a bit in having some reference point for measurement when I was trying to duplicate an actual aircraft.

