Alright so I figured I'd give making a mission a try.
However, I've already encountered a small problem. I want to spawn a NPC (for starters) inside the cave that's already on the standard Risa ground map (west side of the map).
When i just put the npc there it'll spawn on top of the mountain above the cave. Lowering the y to what seems to be a maximum of -32.9 makes the npc show up inside the cave ceiling with its legs sticking out. No matter what I make Y relative to it ends up with the same result.
I can spawn myself in the cave at Y=0 relative to zero altitude.
Why can't I lower the value for Y more? I only need about 8 extra meters.