I won’t touch coastal with a 10’ pole. The fine, long stems cause a lot of impaction colics, and I think you get much better nutritional value out of a high quality orchardgrass or alfalfa mix. Good hay is VERY EXPENSIVE, so I use small-hole hay nets to prevent wastage. Also keeps the horses eating longer, something to munch on to prevent boredom and ulcers. I even feed in haynets outside in the field, thrown on the ground for barefoot horses.
To a degree, you won’t have to rotate pastures too much-- since it’s sand, not mud, acreage can handle a little more horse abuse without getting too beat up. Yes, you will have sandy pits around the gate, the water, and fencelines where horses walk, but unless your horses are really wild it isn’t too bad.
Skin funk is common, mostly in new horses adapting to a new environment. Once their immune systems adapt to the local ickies, I notice the skin issues are greatly reduced. Consider turning out with cotton sheets or fly sheet combos for the first few weeks, to at least avoid skin crud under the saddle area. The BEST product to use for a wide variety of skin conditions is chlorhexidine scrub (Novasan, brand-name). It’s what vets use to prep for surgery and injections. It’s effective on fungus and bacteria, works on garden-variety scratches, cannon bone crud, rain rot, and great to scrub wounds. It’s not cheap, but a gallon of it has lasted me 2 years with 6-8 horses.
There are lots of sand clear psyllium products, but you’ll find the locals rarely use them. Studies at the University of Florida have shown that free choice hay, or feeding beet pulp, is just as or more effective than psyllium. My horses get a minimum of 20lbs hay, and soaked beet pulp (with their regular grain) every day. Knock on wood, no sand colic issues.
Bugs are bad, really terrible except for January and February. Fly sheets, fly masks, and good fly spray is essential. Keep things off the ground and put away in containers. ALWAYS LOOK before sticking your hand in a dark place or picking something up…stinging ants, black widow spiders, and scorpions are somewhat common (shake out your horse’s blankets, too, if they’ve been sitting out unused for a couple days).
