It is my belief an opportunity for a massive time savings would be the ability to place forest elements in the same way as one places groundcovers (grasses). Currently, one can assign trees and bushes, along with groundcover grasses and rocks, to the opacitymap groundcovers system, but the trees lack collision, and render only very closely to the player, as one would expect with groundcovers. Forest Elements, on the other hand, have collision and render to the (perceived) horizon, but must be manually 'painted' over any areas one wants forests. If the map is very large (8192 x 8192, for example), a map-maker could quickly develop carpal tunnel from manually painting so much area. My suggestion is to have a separate system, along side of the forest painter perhaps, that allows for assignation of forest elements, with the same features as the groundcovers system (scaling, density, etc), but with collision and rendering to the horizon. Just a suggestion while I paint away the days.
The Biome Tool is the solution. Thanks to the Dev team! https://documentation.beamng.com/world_editor/tools/biome_tool/