Tree batching inside of terrain

Hey everybody,

After I got FPS drops in my current project I started investigating and found out the problem is draw calls because of the amount of trees I have standing around on my terrain.

When I place the trees manually outside of the terrain as individual game objects they are getting batched and my fps are just fine. But since it's rather annoying to place thousands of trees manually I'd like to use the terrain tools to paint them.

Is that possible while keeping the trees getting batched? Or does putting them into the terrain really only help if they're getting replaced by billboard versions?

My trees have less than 300 vertices, do not cast or receive shadows, I don't need wind or other fancy things.

Thanks in advance