Around here in the exurbs you would absolutely get squatters, crack house, kids partying, homeless people. Might be different in deeper country, but I bet it would still be a draw to partying teens. IME, you get stable tenants if the rent is a bit below market. Maybe you can get someone with caretaker or handiman references, maybe someone older but horse savvy, who can at least fill the house and knows when to call you or the vet.
To date I have bought land and built three homes with horse facilities and I would have to assume that the costs to get power/well must vary greatly depending on the location. Why would horses need a septic tank ? If you bought land with a creek on it you would not need either.
Local zoning may require it just due to the potential for building/rebuilding the home or for sanitary purposes for a barn. Local requirements trump everything when it comes to real estate…
Horses should always be fenced away from any creeks, ponds, etc. on a property if at all possible for multiple reasons: (1) No way to monitor water consumption. (2) Natural water sources may dry up during dry weather, leaving the horses with no water at all if there isn’t an additional source available. (3) Horses tear up stream banks, creating erosion and contamination of waterways. (4) Horses can pick up diseases from water sources contaminated by the urine/feces of wild animals, including but not limited to Leptospirosis and EPM.