One type of place where I have seen RV's forbidden: national parks.
I don't mind too much if the sign said no vehicles over a certain weight or length or height, but I really object when they forbid by function. I've seen this occur where much larger vehicles (a tour bus for example) were allowed and my RV was not. Grrr. I have written to park administrators and have received "thank you for expressing your opinion" sorts of answers but not really any satisfaction.
I bought just about the smallest RV made. It fits into one parking space. It is shorter than the crew-cab longbed pickups that seem to be everywhere. Grrrr.