So ideaget:
The way terrain works right now is that it's like bunches of hills melded together.
Have a modular set piece that's like a brick-made hill, not like siba/soba's ramp, but rather a cube terrain like piece.
And have a mod that turns off bricks INSIDE bricks but makes no floating bricks.
So you have a bunch of hills and you can mold them together, with the occasional mountain (if there's a set piece like that).
And make a "BASE" (16x16, 32x32, or 64x64 cube) that behaves like the set pieces. Then build on top of that and have it behave normally.