There used to be a guy up at the end of my street selling those glass pools. (He does concrete now). The sun was tough on the finish and he had a lot of warranty work.
I suspect the "3 foot" deck rule is really aimed at these types of pools, simply to give the user a safe zone around the water.
Again, the key to safety is bonding. The more you can include in your equipotential plane, the safer you are.
