As an example, we have over 50 macadamia trees in my variety collection, around 45 avocados varieties in the collection, Number of white, yellow, green sapotes, jaboticabas, not counting rarer fruiting trees all happy on the 1 1/2 acres. Been collecting over many years and most are mature trees. Started with CRFG when we had around 100 members, Dense plantings are intentional for watering and potential frost protection. No fruits are for marketing, just a shared collection with others for propagation. Thinning would make the trees unhappy, and me too. The rats are a problem, a challenge, but no great loss of fruit nor nuts since the products are not to be marketed. Our herd of raccoons seem to enjoy the fallen fruits, possums too. If the rats damaged the trees it would be a serious issue, but they do not.
Again, if they have access to your house or attic (called attic rats, palm rats, tree rats...Rattus rattus) you have a problem. Our neighbor had them in the attic, heard them at night, put poison up there, smelled the dead bodies for months. Traps work, are laborious, but make for decent disposal. Amazon has some fine metal rat traps that will last.