One other consideration with tow ratings is electric brakes. If/when you consider a tow vehicle upgrade, some makes almost double the rating with brakes. An installed brake controller is not very expensive.
Andrea a point that I didnt see anyone make is perhaps you don't actually need a trailer that sleeps 3 maybe one that sleeps two and a pup tent would work well for your situation. Those of us who have camped with 12 year old boys know they are often much happier sleeping in their own tent beside the trailer rather than in the same trailer with the adults. Even when camping in black bear country.