I am not for sure how you would feel about this but here is it:
1 - when i was a kid my dad traveled and wore suits on the time - he had these things he would pack in his bags on road trips - the rolled up to about the size of some tube socks rolled up but they were rubber bootie deals that would cover his shoes. he used them in the snowy states to keep his dress shoes from getting yet.
2 - you can also buy a pair of water socks. not sure how comfortable that would be to wear all day long but if you know you want to do more then one water ride back to back, wear them, then have a locker ready and tuck them away when you are done. you can also have a change of clothes or a towel in the locker to help get dry. then you can wear the water socks at the water parks too, everything I read about the water parks suggests to wear them anyway.
some teen agers would get it - too - if you brought the palstic bags. Ask your teen what he would want, wet feet all day or to do that.