Re: cooler storage on swim platform
All appurtenances, essential and non-essential to navigation, must be properly secured.
So, it's a judgement call by the water cops.
Just don't jury rig it too bad, and if it appears to be secure, then you'll be fine.
Imagine an antenna fastened with duck tape and some rigging wire. While there is no official code that calls for x number of screws etc, the water cops would likely cite you.
Think like that with the cooler or anything (like a tube) that you secure down. Make it strong and make it appear nice, and it will never cause them to blink an eye.