I'm very sorry for the delay in responding to your request. I set it aside so I could give it my full attention, and somehow it got lost in my email!
Your instinctive understanding of Lot and his wife is very true. But more than just a warning not to look back, I think it tells us not to disregard divine guidance! The cities were about to be destroyed as a consequence of their treatment of the 'angels' representing the Divine. Hospitality was extremely important in that arid and challenging land; to mistreat strangers was a very grave offense.
Lot and his family were an exception to the consciousness of the towns and were warned to flee to safety. They are the thoughts in our consciousness that respond, even in the midst of chaos, to the loving guidance of Spirit. They were told not to look back, but to keep their focus on moving forward. Lot's wife, of course, does look back and is paralyzed into a pillar of salt. We, too, can find ourselves paralyzed when we allow the security we felt in the past to compromise our faith in the guidance that is urging us forward.