On purple paint, I haven't looked it up but have unofficially heard that it may need to be 12 inches, top to bottom to be legal. I've seen a lot of guys just throw an old tyre over a fencepost, and paint that.
For our ranch, the pipe posts every 100 ft were entirely painted purple
from top to bottom.Big, tall, girthy, permanent, tornado-resistant, heavy metal pipes, dipped in purple paint;
top-to-bottom. so if it goes right down to the ground it's not compliant.
Probably not serious, but you wouldn't want an issue on a technicality.