Hi Damocles,
First I just want to say, Thank you! Thank you! Thank you! for making this world generator. It has been fantastic and I've been spending lots of time customizing new worlds.
I wanted to ask in case this is something that can be done with your current software, but I just may not know the right way to do it. I generated a height map that I liked and then edited the height map to have a large flat area in the center of the map. I've been trying to keep that area all forest without any POIs building there. I know I can use the World Editor in 7DTD to remove any POIs that may populate that flatland, but I was wondering if there is a way within your software to update the DTM file by editing the prefabs.xml and water_info.xml and then generating a new DTM file off of those xml files? I ask because I keep generating worlds off of my import_HM.png or the poiHM.png until I get something close to what I want, but there will usually be something that is still off that I'll have to try to fix in 7DTD's World Editor.