From this site -
clickyTriple towing is allowed in the following states:
Alaska
Arizona
Arkansas
California
Colorado
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maryland
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Mexico
North Dakota
Ohio
Oklahoma
South Dakota
Tennessee
Texas
Utah
I will say this, I really ONLY stay on the East Coast and see a few tripple tows in my travels, I also know a few on the Redwood forum that has done, or does now Tripple tow. They have stated that they have NEVER had a second look from a LEO.... They were told by a couple of LEO's that unless you really LOOK UNSAFE, you wont be bothered.