Gravel is by far the best parking surface for RV Storage!
It's a common misconception that (hard top) concrete or asphalt parking is better. Hard top is not about protecting your RV. The truth is, Asphalt and Concrete parking lots are far cheaper for the owners to maintain, and that's the only reason other storage yards use it.
Think about it. Concrete and Asphalt parking lots get very hot. Asphalt and Concrete parking also gets very dirty. Asphalt and Concrete lots get even more dirty when it rains. So, by parking on Asphalt and Concrete lots, your RV fries in the heat, and dirt is constantly stirred up or splashed up when someone drives by.
On the other hand, Gravel parking keeps your RV cooler and cleaner. You can walk barefoot upon a gravel lot anytime of the year. Don't try that on an asphalt or a Concrete lot! People naturally drive slower on gravel, causing any surface dirt to settle, not become thrown into the air! And when it rains, a gravel parking gets a thorough cleaning, while hard top lots become mud puddles.
As RV owners ourselves, we have parked on both. That is why we chose to have a gravel parking lot at Astra. We chose gravel in spite of the fact that it costs us a whole lot of money each year in maintenance. We pay extra because Gravel is by far the best parking surface.