I would say that the white cannot be use as a hot phase leg. Not sure if it is legal with flexible cord to re-identify it though. Might have to use 5 wire SO cable.
You say that it is fed from a 50A breaker. That doesn't look like #6 to me and is the plug/receptacle rated at 50A?
That cut off ground rod is a joke. A ground rod is not needed anyway.
-Hal
