If you scan/photocopy the piece of map you need for a specific trip, you can always write in what you want without spoiling the original map. There's also a LOT less bulk and folding involved, which was really the original question.

If you do this, though, be sure to include the bail-out points, especially for long hikes! You never know! I've had to do this only twice in a long lifetime, but that was enough.