Is it possible to do textured overlay with seeing terrain in mind , if a texture is overlayed its difficult to see the ridges and mountains your flattening etc. here is a concept
For smoothing areas around citys its difficult to leave out parts without smoothing onto them at times. Is it possible to Select an area with a polygon line tool to not interfere with tools
heres a concept , The red zone would be unbrushable by tools
and lastly , A water only Mode overlay on textured Mode