I like 17" high Gore-Tex snake boots, or some other waterproof variety, compared to snake gaiters. Cabelas has them on sale occasionally --- I own two pairs. I also own a pair of snake chaps. You'll probably need both... especially if you survey snake infested places --- like on some of the islands on the Cape Fear River, in North Carolina --- like I've had.
Copperheads...will sometimes snake coil in a circle, with it's head in the center of the coil --- poised too strike straight up. The strike could go inside of the snake chap legging --- that's why I would go with the snake chaps and gaiters/snake boots.
Water moccasins will sometimes try to avoid being stepped-on by a human. That's why you should learn to hear for a rustle in the leaves or weeds, as the water moccasin try's to avoid you.