That turned out not to be such a fantastic idea. It's not that it didn't work, but it made the individual pieces a lot more troublesome to lay out and to pick up afterwards.
So, now that I'm on a bit of a terrain-building kick, I've got on to actually making some roads out of the pieces, and I'm starting by cutting off the interlocking tabs. A good sharp saw takes care of that with just two or three strokes, so it's not a big deal.
I'm not completely sure that this is a necessary step; I'll finish one section without carving to see if the difference is noticeable enough to make it worth while carving all the others.
I did consider adding a bit more vegetation along the sides of the road, but I decided against it as it would make the pieces a bit more difficult to stack and store.
If I decide later on that I'd prefer them a bit more overgrown, it's a simple matter to add more crap.
This piece hasn't had its wheel tracks carved out, and to my eye the difference is pretty minimal. I can tell the difference, but I'm not sure if that's because I know it's there.