Are you worried about tornados just when you're out on the road, Drew, or at home, too?
If just out on the road, you could just get in the motor home and drive away from the storm, couldn't you?
FWIW, I made up some stakes from 3/4" diameter hot rolled steel and drove them into the ground at a 45° angle using a Harbor Freight jack hammer. Four stakes, two feet long, two pairs. One pair at the front and rear of the office trailer here. Then I ran 1/2" steel cable up over the frame rails of the trailer between each pair of stakes. There's a turnbuckle in the middle of each cable so I can put tension on the anchors. The trailer wasn't moved at all during last December's wind storm that took off the porch cover, which was only a few feet from it.