Unity trees in terrain system [ISSUE]

So I'm creating a game including low poly assets and I would like to keep that theme throughout the game, however, unity's built-in tree system only allows for realistic trees, not low poly trees. I've tried importing my own mesh and then painting with the detail painter, but it paints them sideways with no material. I really want to use the terrain to paint my trees instead of placing each one by hand.

Any suggestions?

 

I think trees you paint with terrain need to have the mesh renderer/etc in the top-level gameobject to show properly.

 

I've managed to get them to render correctly, but they're still sideways, any ideas on that? If I rotate the tree they still paint sideways.