Also, unless you're planning to patrol the entire length of the convoy, which will be many, many miles long and unlikely to be practical, there will always be people wandering into your restricted area and leaving presents behind.
And if you're abandoing a whole load of ammunition and materiel to make a quick getaway, you've just armed your opponents with your own equipment.
There is no good here. However you look at it, any forced retreat is going to be a disaster of epic dimensions.
Ammunition or other things left behind is not handed over to the enemy - it is blown up. Peak oil is not an energy crisis. It is a liquid fuel crisis.
As for the desert route - with what trucks, exactly?
The big airports will be the first missile targets, and as soon as those are gone - and it's wonderfully easy to crater a runaway - the supply lines are cut and the clock is ticking.
Best of luck with a quick getaway after that.
