As a retired concrete contractor, I would agree with Valhalla 360, but would add.
The concrete mix for a outside home owner slab mix should be at minumum 3500 psi to 4000 psi and 4 inch to 6 inch thick, with or with out rebar depending on building codes, depending on the weight of the RV, but at least add fiber to the mix. After finishing, We spray a curing compound on the surface which holds the moisture in. There for no need to wet down the concrete during the curing stage.
Some areas of the country require a higher psi, because of freezing weather. Example: Lake Tahoe requires a 7 sack/4500 psi.
During the winter. We would use hot water in the mix, along with calcium to decrease the curing rate. increase the curing temp and cover with concrete blankets. This does not decrease the strength.
Lillyputz
