Commission: Easy to use worldgen editing tool for rain and forestation heightmap scales

[SoupInCat]

Just as the title says, the ability to easily edit the scale of rain and forestation heightmaps to allow for much larger desert regions, much larger forested areas, much larger grasslands. I just want each region to be larger such that I walk into a desert and can see only desert for miles, as well as more gradual transition between regions. I'll pay whatever mod dev's think is fair, within reason.