I am going to be the voice against gravel. I bought my current house and original owners had gravel at side of house, next owners rented house out and gravel wasn't maintained. when I bought the house, had no TT and spent 3 years trying to get random loose gravel out of grass area on that side. My plan for my current TT is to get concrete pads approx 24" square and 4" thick from concrete company. I think they are used for mobile homes (but not sure). They are thicker than ones from box stores and won't break so easily, but can be easily set to level and easily removed if not wanted at house sale.