Correct settings for exporting a projected mesh/ground poly with blender addon?

Does anyone here know the correct setting for exporting projected meshes? I
know everything has to be joined into one object or make parents, but some
layers are exported with a different scale and orientation.

There is nothing wrong with your the export option ( i don’t like loose
edges/vertex to be included in the geometry so I keep also those disabled)
Projected mesh is just one single flat mesh If you need more layers, my advice
is to export them as separate objects and let the sim do the layering with
priorities: if they share the same origin point, using the gizmo transform
window you can copy the coordinates from one to another! Also make sure to
apply all transform before exporting