You'll need an agreement about who carries insurance - liability for riders and hrse handlers getting hurt is you - but who carries insurance on buildings? Also things like air conditioning/heating, water heaters, etc... Lease must spell out who pays for fixing and if owner fails to get repairman out within 2 calendar days leasee can pay for repairs to a licenses/insured contractor and deuct that cost from monthly leasing costs - or something like that.
Then ensure you have ALL that equipment inspected and issues fixed BEFORE leasing the facility, with your independently hired contractor doing the inspections. In Fla we've heard of resturants/gyms/etc being leased where they expected leasee to pay for new/repaired air conditioners, and even leaky roofs - so have it spelled out so there is NO quetion of who repairs fencing, water lines, stalls, etc.
Neither you nor the owner want to think the other guy is paying for it - one of you would surely be disappointed!