I'm NOT an experienced Airstreamer, but I am an experienced ocean boat captain. Hunker down with as much security as you can manage.
If the big one comes ANYTHING will help. The AS is pretty solid on the ground at the wheels but the weakness is the possibility of the front or back blowing around. Anything you can do to stop the AS swivelling will help. Ties/anchor rods driven into the ground, or ropes to a tree or a lighting column would help. Tie the AS to your truck, or even try hitching to the truck during the storm will help. The stabilizers need to be tight but actually won't help much if they just slide. Make sure you have as many secure 'anchors' as possible. Tie up to anything and everything. As a storm passes the wind force comes from many directions.
I'd suggest parking across the wind, rather than head to the wind. The tires will provide a lot of resistance sideways, and basically no resistance to rolling head on. Of course chock the wheels - chocks, firewood, stones, bricks, anything.
Lastly - avoid trees if you can. They promise shelter but can be deadly.