Texturing workflow for extremely large meshes?

I’m struggling to figure out how games texture large environment assets like in Destiny. I know there’s tileable textures involved but not sure how it’d apply to something as complex as a giant tree like the example below.

I think painting a color ID map could be a good way to go.
Black for the default texture. (tree bark?)
Red, Green, Blue for variety textures.
Then tell the UE4 material to apply your tiling textures to the spots that you painted via color channels.

I would give each tree it’s own material, I think 2 materials should be enough for this.
2x 4k resolution color ID maps could work I think. Depends on which target platforms you have and how good you want the graphics quality to be.