I do not know what the law states in Arizona, but I have seen an "Arizona Safe Boating" publication that stipulates the 20' rule. If the officer wants to write you a ticket for "unsafe boating", they can, regardless of the law. We had a similar problem here in Austin; however, everyone that fought the ticket was found "not guilty". It is no longer a problem.
Rumor has it that the 20' rope rule was introduced by a boat manufacturer because of their concern for Carbon Monoxide. Our studies have shown that the people in the boat get far more carbon monoxide than a wake surfer.
The 20' rule is still being promulgated by Supra/Moomba on their website. On my list of things to do: contact them about their erroneous information. All Supra/Moomba owners should contact them and raise hell.
If you ever need help fighting a 20' ticket, our studies, and those performed by the CDC are on our website at www.FreshAirExhaust
If you need help, contact us.