Increase squaresize, but keep original terrain scale?

I currently have a map with a squaresize of 8, with the boundaries/out of bounds grids pushed all the way to the edges. I'd like to increase the map size (to 16, for instance), but keep the original scale/proportions of the terrain. Essentially this:

http://i.imgur.com/0e3mey4.png

That was done by simply scaling down the heightmap terrain to 180x180 but keeping the overall image size at 256x256. Sadly this won't work since it scaled down the terrain, and I want to keep the original scale but simply extend the OOB grid. I just did it to give you an idea of what I want. I've messed with the scale property for the TerrainBlock, but that doesn't appear to change anything. This is using the Torque Juggernaut engine to be precise, though I understand it's pretty close to TGEA.