Helmets weren't designed to have your hair piled up on top of your head. The fit isn't correct.
I french braid my hair, cover it with a hairnet to keep the wisps that always escape in. The braid is done up like a hunter braid with a clip/net combo like you posted. It's not this bun that hangs down my back, but looks like a little button under the back of my helmet.
Your appearance needs to be neat, but it should also be safe. As long as you don't look disheveled or have a ponytail hanging out the back you should fall within the guidelines.
If your horse says no, you either asked the wrong question or asked the question wrong
And God took a handful of southerly wind, blew His breath over it and created the horse