Heh, it’s even easier than that. Just delete everything but [character name].sav, close the game and restart it (this may or may not be necessary, not sure if the game still loads the world only on startup). Next time you load a save, the game will regenerate the world. You can’t keep the vehicle though since that’s part of the map. You’d have to dismantle it first and carry the pieces which would be pretty hard without cheating. But otherwise it works, I do this all the time.
edit: master.gsav doesn’t get regenerated correctly so don’t delete that either or the game will crash on the mission screen. Of course if you have NPCs off that doesn’t really matter.