The hanging blocks are a good idea CA. We do much the same at the beach for our 10x10 shelter. We take 4 of the cloth shopping bags and fill them with sand and hang one from each corner. Holds much better than any stake in the sand. We saw a wndstorm take out all umbrellas around us but our shelter stayed strong.
.... And no, sorry I do not know any exorcists.
.... And no, sorry I do not know any exorcists.