I wrote the lower portion before finding this article. Hope it still makes sense. I believe RIVA limits their certification today at 430. I don't think it's a legal requirement. This is an older article on subject.
http://www.rvbusiness.com/2007/03/rv...quare-footage/
This link discusses changing regulations. Appears Park Models and RV need clarification?
http://www.mhmarketingsalesmanagemen...-housing-code/
Can someone give me a "statute" or cite number? My understanding was the size is limited by weight, length and how wide while traversing the National highways. I believe the 3750 and 3850 Montana has the most sq. ft., never measured mine, I will next week! I was looking at another 5 slide model that had narrow slides. Last but not least, several manufactures make 50 ft models, multiple slides? I know some like "Continental" have units in excess of 500 sq ft. The last thing, might be how big without special permits. That is an entirely a different conversation.