I had a look at why the tree, forest, etc. collisions were not working since some Assetto Corsa patch and it turned out to be easy to fix so here is another update for Joux Plane. I improved the tree collision models as well, they no longer throw you around the track so much (rather you seem to now sometimes get stuck in them. Oh well).
Download v1.4 of Joux Plane from here.
Get version 1.41 from here.