u must do 2 thing:1) in the mapview that tile you must leave the floor empty(so it can be filled by the terrain, make it an object or wall)2) also in the mcd it must have no ground and be transparent (no grass)
I guess I just need to combine the walls with the floors.
Yes, you can do that if you have free slots, but you can also take the half-floor tile and place it as an object, or a wall. It should work.