This may not help your particular situation, but there are some green cabins immediately next to Cove Harbor that are perfect for people bringing a boat and want it to be safe. They have a parking lot designed for boaters (every cabin has its own space for truck and boat), free cable, wi-fi etc. and it's about half the cost of a Rockport Hotel. 361-729-7500
If you want to fish a pier, there is a free pier at the beach, as well as the State's largest lighted fishing pier in Copano ($5 a rod or so).