How can I secure a shed with a skid foundation in a windy location?
By looking at some mobile home anchoring systems you might be able to adapt something to a smaller scale. They appear similar to the screw in the earth anchors used for dog run tie outs albeit on a larger scale. I would screw in three dog anchors on each side and use a ratcheting cargo strap (available at any auto parts store) to cinch it down. It may take two straps hooked together to get enough length to go over the roof.