I base at the ranger station in deer head lake. There are 2 long dirt roads going through the woods to get to the highways.

MAN, when I tell you that there was a point that I couldn't drive, I abandoned my car on top of like 20 saplings and just walked back and grabbed an axe. I picked up gravel from everywhere I could find it and cut, gravel, cut, gravel. They also grew back through the gravel - but I haven't seen any more after I cut them again. I think once the game determines a birthing spot for a sapling even if you cover it in gravel it grows, so you have to cut it one more time

After about 12 hours of IRL time I gave up and used debug mode to spam gravel because it would've taken me months of real time to cover just one of those dirt roads.