I'm not sure about the Gulf Intracoastal Waterway but I believe you are not permitted to take up residence in any intracoastal waterway because it might be deemed a hazard to shipping?
Perhaps if you were constantly underway and paid the local use fees you could technically live on one?
I don't think it would be like having a houseboat on a Louisiana Bayou?
The Gulf Intracoastal Waterway is a 1,300-mile man-made canal that runs along the Gulf of Mexico coastline from Brownsville to St. Marks, Florida. The Waterway links Texas ports with the rest of the country and enables the state to handle more than 50 percent of the Waterway's traffic. The 423-mile-long Texas stretch handles up to 90 million tons of freight annually.
It allows ports on the Texas gulf coast to be key hubs for shipping throughout North America. They are at the center of the state's multimodal transportation plan that combines trucking, rail and marine shipping.
The Waterway is part of the larger Intracoastal Waterway that includes a stretch on the Atlantic seaboard, from Key West, Fla. to Boston.
See Chapter 4 page 11
http://static.tti.tamu.edu/tti.tamu.edu/documents/TTI-2013-12.pdf
Concerning part of the waterway in LA
http://www.federalregister.gov/documents/2018/07/03/2018-14244/safety-zone-gulf-intracoastal-waterway-lafitte-la
