@Anonymous @Tina6942 depending on the locality, discriminating against families with children may not be legal; maybe consult a local real estate attorney on that.
Re. liability, I suggest the first thing to do is talk with an insurer who covers vacation rentals, e.g. Proper or Foremost.
We rent places on a lake, with boats, and our insurer has specific requirements re. house rules and signage, but does not require guests to sign waivers.
Ultimately, if you are going to be permanently stressed by renting a property with a pool, I would say it's probably not worth the mental health cost.