However, we can have one person come around to the site once in a while. Any suggestions should be able to take heavy winds. We don't want anything that's too expensive. We are able to spend some money on the solution but we do not want to be extravagant. Be aware that the exposed plaster can be damaged by water during the off- season.
Rain is the obvious source, but there is also water under the ground, trapped in the sand.
As the weather warms up and heats the sand, some of this underground water needs to be able to escape. On warm days we've noticed condensation on the inside of the plastic covering the underground chamber.