You need to come up and stay at Salisbury State Park in Ma. They have huge cement anchors in the ground each side of the site pad. Each anchor is 3' in diameter and equipped with a 3" ring. This is totally un-freaking believable... Who in their right mind would want to weather a storm there? If its bad enough to either blow you camper away or wash it a way with a storm surge, Why would you want to be there? Knowing the way the state of massachusett works, in the event of a storm like that the Park would be shut down and locked up anyways.
The only useful purpose for these anchors would be is to tie up you dogs. Or to get someone like me to think about all the possibilities while I sitting there enjoying a cold one. Only an engineer for the government could come up with idea like that!