Limited time advice

You can find all sorts of combinations and contortions by people trying to find ‘the best experience.’ Use the search function to find many of them. My advice is to simplify the work and once you start somewhere, just keep walking until you are out of time. Wherever you are, it will be great.

If you feel the need to finish in Santiago, then start somewhere to make that possible. How far can your young children reasonably walk each day? That will determine the distance you can cover (Your post isn’t clear whether you are bringing them, or if you are escaping them for that time .)