I just bought a house for my daughter and SIL with a huge area for my RV's and they won't even be able to see them. An area of 58' long by 25' wide and its 30' from the front property line that starts at the sidewalk. I hope to develop the area in the very near future, but I'm not sure what the city will say, or need to build a structure on that part of the property. I'm pouring a 58'X25' at ____ inches thick (fill in the blank) slab that will have a block wall surrounding the area with gates in front, that I'm doing in May. I've been told to pour a 6" slab at a 3000 psi mix, but the dirt removal will be a huge expense just to get rid of the dirt, but I want a 4" slab with a 4000psi mix with rebar reinforcing it. Any opinions would welcomed on the slab, BTW my 5ver is around 11K dry weight, with a 3500 lb. boat.