If I was overly concerned I would take some old axle shafts and try to drive them through the several feet of crushed concrete and other rubble that composes the driveway area where I have the tent located.
Last year when I had it set up at 25 by 30 ft size I had 2 80 lb truck brake drums located at each of the 6 posts and a few hundred pounds of chains on it, the tent then was tall enough to drive the tallest legal height semi trailer under . We had a storm with wind gusts over 60 MPH the tarp got ripped up some but the structure never moved. I have it located now between my 1968 GMC buss conversion motor coach and my 45 ft house hold goods machine shop trailer it is pretty well protected from the most severe winds and is not much taller than the motor-coach at it peak of the tent so with 20 27 ft long 3/8 chains hanging on it I doubt it it will move too much if the winds don't get above 60 MPH