@Chohole: I know, I was only kidding. Your trees are great and it’s a great idea to build your own.
@Horo: I’ve made booleans out of metaballs in the past, I don’t think I’ve tried it with trees, but will have a quick look this evening.
Meanwhile taking the photo Chohole posted of the country lane with overhanging trees, I knocked this quick scene up (it took an hour to set up and 30 minutes to render using Premium, TA and soft shadows at 4RPP and Max Ray Depth at 1 hence the noise).
It’s only rough, I only did it to give an impression of what can be relatively easily set up. Given more time (and I may work on it more because I think it’s looking good[ish]!) I could look a lot more realistic. But if anyone wants or needs to know how it’s done, I can go into details.
Click thumbnail to see full-size image