thanks for a great report.... it nice to hear reports were the 'boat was pushed out' you discribed it exactly what I thought when I was in deep soft sand in the sahara over 700km from anywhere. I had only 10pound pressure in my tyres.... do you reduce your tire pressure? if you carry a small pump between you could try it. It certainly makes a difference to the LC.
If you did it again what about using the dunes, as you said it was firmer to walk on!
all the best for you future adventures am sure you will find somwhere else to 'push the envelope'