I can help - I’m horsey and have a husband also in the medical field that likes water. I don’t do cold weather at all.
Skip Myrtle Beach. Not horsey enough.
Charleston could be an option. There is a small equestrian scene and I have one horse there currently. Have access to vet/farrier/trainers but it’s limited. The restaurants/shopping/amenities are the best you will find in SC and stunning water views everywhere, plus beaches and ocean. Easy access to hospitals. However the population has exploded over the past 10 years or so. It is very busy and land is very expensive. The land in the low country is also not ideal for horse keeping. For those reasons we chose not to live there full time.
Aiken is an eventers paradise. The equestrian amenities can’t be beat. Excellent show grounds, trainers, vets, etc. Land is still affordable and great for horse keeping. My husband would not be happy with the hospitals and lack of water though. I also don’t love the actual town of Aiken but the equestrian property and Hitchcock woods may make up for it. I enjoy showing there and love to stay/eat at the Wilcox. Worth a visit.
Tryon is beautiful but too cold for me, however may be mild compared to what you are used to. Easy commute to Greenville/Spartanburg for hospitals. Top notch vets, trainers, farriers. Also worth a visit.
Consider Camden SC. Great fox hunting community. Access to vets, farriers & trainers that are good but not quite to the level as Aiken/Tryon. Cheap land good for horses and low COL. Access to Lake Wateree. Husband would have to commute to Columbia or Florence for good hospitals (about 45 minutes). Charming but VERY small town. Ultimately too small town for me but worth a visit, if only to visit The Tack Room (trust me on this).
In the end, my husband and I ended up settling in a mid size town that isn’t horsey but with a good hospital system. I am just close enough to Camden that the vets/farriers will come to me but I have to commute to train there. We are close enough to Lake Wateree and the beach which satisfies my husband. We still enjoy low cost of living, no traffic, and very mild winters. We all compromised a bit but it worked out well for us. Good Luck!
*an edit to say don’t underestimate the heat and humidity in Camden/Aiken/Charleston. Make sure you ok trading a mild winter in exchange for a brutal summer (I love heat so it’s not a problem for me, but some do not do well in it). If that’s an issue, look more at Tryon and Southern Pines.