One thing from when I stayed at RPR. We are early park people and the boats weren't picking up in time to get to the park at opening. Its easier/quicker to walk to IOA than to take the water taxi.
the water taxis start early before the park opens.
did you go in a low season time?
i had no issues getting to the park/city walk at 8 in the morning using the water taxis last year.
last water taxi out from citywalk/parks will be at 2:00 in the morning.