I thought about lip up, but most of the shelves don’t have a lip (that’s what was on deep sale), so I went lip down for consistency. I’ll put some rope (I have a lot; I am an offshore ocean racer) under the landscape cloth to define the edges. That or foam backing rod.
Speaking of foam backer rod, I am considering coating some with adhesive and rolling in ballast gravel to act as a sort of positioner/retainer for the track ballast.