Just skimmed over the responses... but keep your money in your pocket. Reference the concrete only, let's put this in perspective.
Campers are not heavy (ok, compared to a bicycle, it's heavy). Worse case scenario is 1500#s per jack. Big friggen deal. Your typical loading dock parking area is only 6" thick. A nominal 4" slab is totally adequate. Rebar is a complete waste unless your primary reinforcement is garbage (i.e. substrate). There's a reason there is rebar in bridges and not in concrete roads.
Don't get me going; I spend an inordinate amount of time on this subject. There's a rule for forums that doesn't get followed much; conversation is good, speaking as an authority outside of your expertise is annoying. Please note, I don't give advice on mammograms, diesel additives, or conductive properties of a wireless bra.
Now, what was the OP's question?