Great suggestions here- and work with your agent! Insurance agents for stuff like farm insurance sell policies from a bunch of companies and should be up to date on who offers what kind of insurance, at what kind of price. It’s definitely niche insurance and you need a proactive, experienced agent to help guide you to appropriate coverage at fair value.
You need general liability, care/custody/control, and probably an umbrella policy too, perhaps tied in with renter’s insurance. An experienced ag agent should be able to tell you if the renting angle is going to be a challenging aspect or not in your area.
You also need to think long and hard about worker’s comp insurance, if the current operators don’t carry it. It’s quite pricy but critical to be legal and to protect yourselves, unless you will have no employees, Several good threads on it here recently.
When I opened my commercial stable in litigious California (which has no state-wide equestrian liability framework, like almost every other state) I was actually surprised at how affordable my insurance package was. Mine has my homeowner’s and the above mentioned policies rolled into one. My agent does nothing but equine/equestrian insurance and is a horsewoman herself- she’s been great to work with and ask about things.
Put your insurance costs on your boarding stable cost worksheet (you ARE doing a very detailed cost spreadsheet on this venture… right?) and ascribe a value per stall. Your insurance is a fixed cost- it won’t adjust if you’re full or have a few empty stalls, you have to pay it regardless, so know your operating costs.
It costs me about $83 a year per stall for the coverages I carry and has only changed by a few hundred dollars over the years. That is a million dollar policy on the first two coverages and then a million dollar umbrella. We don’t do shows, offer trail rides, and i don’t teach.
Trainers at our place must carry their own insurance and name me and my business as also insured on each policy, and they have to cover their grooms/assistants too. Your agent can be very helpful in getting you off on the right foot for insurance for everyone who may use the facility, in different ways.