Lighting a massive amount of distant trees in a mountainous landscape?

Hi all,

My project has a massive mountain covered in trees! I need to light them dynamically and distantly, the best looking results I have achieved has been with Distance Fields.

let’s start with the pics, the first has no Distant Field lighting on my sun and you can see all trees are bright. The second has DF on my sun and looks far more natural.

Problem is, with DFAO distance cranked up FPS takes a huge hit AND there are flickering AO artifacts (seemingly due to a hard coded limit in DFAO meshes per scene…d-shadows.html)

How else could I achieve shading on my distant trees? Thank you!