You said that your home needs to be "tied down". I'm assuming that you have a newer model with steel cables that come out of the bottom every 16 to 48 inches. If this is true than your home should be high wind / hurricane rated (If I remember correctly 120 mph). Studies have shown that most mobile home disasters, that leave it looking like a dropped box of stick matches, have happened as a result of the storm being able to remove the roof causing the structure of the home to greatly weaken. To combat this the manufacturing regulations have changed to include cable tie downs that start at the bottom of one side, go up the wall, over the main roof structure, and down the wall on the other side. If your home was setup by a knowledgeable and licensed mobile home company you should be OK. No wood structure can withstand the brute force of a higher category tornado throwing debris at it, but the cable system should keep the main structure together in 99 percent of the wind experienced in a storm.
Paul