Our foundation on our new RV/truck barn was overkill I admit and was mostly due to my specs but did not want any slab problems. It is a monolithic slab (no joints), 6 inch thick with additional 18 in thick by 24 inch wide beams around perimeter plus two similar sized beams down each side of central bay where RV will be parked. Six #7 bars in each beam tied into #5 rebar grid 16" OC. Also has brick ledge around perimeter to add stone wainscot to match house in the future.
Also added a threaded floor drain which is located just below where the RV utility basement compartment will be. Concrete contractor sloped concrete 3 feet around and down into drain with a 1/4 inch per foot pitch. Has the recessed (slotted style) cap.
Getting the slab coated with commercially contractor applied epoxy next week.
Will add 6 inch driveways with somewhat smaller perimeter beams next year.