Had another thought.

Bugging out for a family with three small children, esp. for any distance, really requires a vehicle. It also requires you being able to get through traffic, fix anything that might go wrong with the vehicle, etc. Taking to foot or some other mode of transport while enroute is going to be difficult.

All this means that you must be prepared to bug out early. We all should be, but families with children really need to be out early.

This involves preparing the minds of your wife and you to think this way and not much else.