I've made a new harvestable tree, but how can I get it in multiple places in the world? It's way, way too huge for me to be able to. I'd have to place maybe a thousand total. I can't do that manually.
I'm no expert by any means, and I could be wrong, but I have never heard of a way to place more than one tree at a time...At least not in a worldspace already created. I think you are just going to have to place each tree manually. I know it's a tedious process, but many aspects of creating mods are tedious.
Maybe you could reduce the amount of trees and place them more strategically. Like maybe just place them near roads or something.
Chech this: http://www.creationkit.com/Object_Palettes