You further need space between them with each other and the edge of your property for a host of other reasons such as being able to inspect and paint each tank. Thus looking at actual facilities is going to give you vastly more resources options than just looking at the footprint of each tank.
BTW - If everyone followed Elon Musk's projection of 100 x 100 miles of Solar; then the US would not need these fossil fuels. See : https://www.reddit.com/r/Futurology/comments/1vq0uu6/solar_i...
As the article points out fire is a real concern here, which is one of many reasons making salt caverns so appealing. But it’s also a major driver for distance between each above ground tank, you want to isolate risks so a single failure doesn’t propagate across the facility.