I have never been to the poly so I don't know about their pool policy, but I know SAB does rent iner-tubes to guests, but I am not sure they allow you to bring your own (I have never seen anyone with their own). I doubt they will have a problem with arm floaties, but they may want a parent to stay with the child who has the floaties just to make sure nothing happens to him (or her).
I don't know if your 3 year old will have a desire to go down the waterside, at SAB, but they will not allow him down unless he is able to swim on his own. I.E. without floaties. But there is a mini pool, at the entrance to the large waterside, meant for kids and it is equipped with a small slide.
I don't think SAB allows any other type of pool toy in the water, such as balls or noodles, probably because there is current in certain areas of the pool and the toys may get away.