The only time I've been to Alabama and didn't run into folks was at the Sipsey Wilderness (located within the Bankhead National Forest) but that was several years ago backpacking. It maybe visited a lot more now and not sure that it would meet your yak fix... but it is isolated and I assure you that you won't see any one on a jet ski. :-) Good luck finding a spot... it will be a tough weekend finding an empty lake on Memorial Day weekend!
Paddle Straight and Prosper
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Old Town Discovery 158 Canoe