Maps in BOB?
Something I have not seen suggested yet is to carry maps in your BOB. You may know where you plan to go, but alternative routes may be necessary due to blockages, etc. A good set of topo maps should be included, also, for any situations that might require you to walk or scout around.
If the bo vehicle MUST be abandoned, it has been my experience that relatively healthy children over three years of age can travel 10 miles per day walking.