Re: How to handle changing at pool?
You could always take a big shirt with you put it on & slip your arms inside of the shirt & take your bathing suit off. Then put your arms back into the sleeves put your under ware then shorts on all while the shirt is blocking his view. Then put your arms back in and put your bra on back wards so you can hook it with out flashing him, slid it around and pull it up so you are wearing it as it is meant to be worn (sorry if I worded that strange I hope it makes sense) Thats what I would do.
I agree with the others it is not safe to leave him alone someone could walk off with him in a split second. & the locker room well a lot of people are not very modest in those place's so that wouldn't work either. So I would either change in a tent shirt there or ride home soggy I hope this helps