if you are not charging then the visitors are invited guests, most likely your homeowners policy would provide some level of coverage. (review the policy and if any questions ask the agent, if favorable request the answer in writing for your records)
We were very specific with our carrier that we had animals and often had visitors. This was written specifically into our policy, the policy does say all of animals we own or care for their actions are covered for liability and or injuries up to the policy limits. If a claim is made Rightfully or Groundless they will defend us. (claim of injury must be made within three years of incident) (The policy also covers uninvited guests covering the attractive nuisance aspect of cute animals )
We once had an ongoing Farm here, but as time progressed it was not needed so we dissolved the corporations transferring the horses to private ownership (our kids and wife…technologically I am horse/pet free)
Appearance wise, there is no difference between then and now, one who was to come would not have known there once was a success boarding stable here (well the stable boarded my business’s horses)
Then put a tip jar up for donations so your guests can show their appreciation for the visit, might have little sign saying a bag of feed is $25.00