Booleans Mini Tutor: Impression

[maker]

That's why I'd like to try to find solutions using both approaches

Here's one approach, using bits of your and ggaliens' suggestions.

To simplify matters, I've assumed one side of landscape along road "lower". (Easier to select & modify segments which are not satisfactory.)

I think this is better. Hopefully, it actually is



Edit: Attached the wings file, if anybody wants to play with it. road_on_lscape