Increase distance field AO

I’m currently running into a problem with the distance being used on distance field AO. We are using a larger landscape (~12 * 8 km) and we need to populate it with trees. I’ve been looking into multiple methods, including the kite demo examples. Everything is fine expect the DF AO showing only in a small radius around the camera, while DF shadows work on the whole map. Increasing the distance in the skylight’s attributes doesn’t change anything.
I’ve been looking into commands increasing the distance, but that all seems to affect only shadows, not AO.
So I’m wondering if this is a hardware limitation (running in dx12 as well dx11, same result), or if there is a way to fix this. I tried scaling down the entire level and that resolved the issue, but that meant my scene was no longer accurate.