Randomizing the tree spawn was easier than I thought. Didn’t have to adjust Z for the hills thankfully. 
I generate a miniature(or you could say monster by the look of the function) version of my vector field for the trees. This is done only once at the start of map generation and each of the 37 trees placed in each forest already has a predetermined offset compared to the center of the tile it is spawning on.
And then I use that vector offset array to reference when placing them, while giving each tree a random x/y bump from its grid point. This is done once per forest to be spawned.
