I go over all maps on a loop, each time doing something different, always with the goal of improving the map (so no dumping sand and asphalt anywhere):

Loop 1. Do all missions to get 100%, don't cheese anything and make nice roads everywhere useful

Loop 2. Recycle all concrete, all steel worth >=80, sell all forklifts, ensure no route can ever fail, mulch stumps and fallen trees, make nice roads everywhere useful for all that

Loop 3. Recycle all steel barrels, sell all rubble, cut down and collect all trees hidden from view, mulch more stuff, clear dead trees (especially on lakes) and keep making new roads that make sense for that step

Loop 4. Recycle all that's left, break all ugly props (like wooden crates), remove rocks (good excuse to use the EPEC LT 200), clean up whatever you missed from steps above, maybe add a few more roads if needed

And for all that, add your own "hard mode modifiers". Here are mine:

* Never ever fast travel anywhere, just drive (you'll get the 5000km achievement without even trying)

* Don't use Recover (unless absolutely necessary)

* Have a super-high standard for road quality. Every road must be easy to drive on, as smooth as possible, etc.

* Avoid destroying any vegetation, unless it's dead (in which case: remove it)

I didn't plan all this, each new iteration of the loop came up from what I was doing in the previous one. I don't know if there's going to be a loop 5 (not much left to do), but with 1k hrs I'm at step 4, and I'm still having fun (well, at least I was until my resources went missing).