Unfortunately I have first hand experience with doing all the
wrong things on the beach. I buried my 86 trooper up to the
axles because I ran onto the beach without dropping the tire
pressure enough. I was lucky that one of the local service stations
had an off-road tow vehicle and also happened to be honest
and fair. Needless to say, I now know the proper way to
navigate the beach by 4x4 :>).

I am mostly concerned with whether the 4WD system on the 05
Mariner can handle driving on sand. For 05, ford switched from
a mechanical center differential with lock (used on '04 and earlier
escapes) to an all automatic, electronic system.
From what I've managed to dig up, the 05's run in front
wheel drive mode until the computer detects wheel slip.
Then, through an electronically controlled clutch pack, it applies
power to the rear wheels.
My first concern is that the truck will not go into 4WD mode
until some wheel slip occurs. From my experience
wheel slip + loose sand = trouble.
My second concern is that the stress of this kind
of driving will overheat and possibly burn out the clutch
pack.
I know I'm grossly over simplifying how the system works.
If I had a better idea of how it worked, I might not
be so concerned.

- Vinny -