It's not easy from my perspective.... and yes special challenges in Florida - if it's not too much salt from the sun beating down evaporating the water, then it's too little salt from the rain pouring down and overfilling the pool.
I have the pool at a very slight angle so overflow goes out one spot where I have drain tiles on the ground, and a small stock tank filler to keep the water level consistent, so mostly I'm dealing with low salt.
I was thinking if there's no automatic sensor doohickey around, maybe I could rig up some sort of poolside storage thing where I could let out some salt into the pool as needed - maybe a modified pet feeder or some such. I don't have a garage so protected storage is an issue.