This paracord boonie hat band has a single pass of a two bight turks head knot(2 bight 49 lead), with a doubled up 30 foot long length of paracord. It still looks similar to the last hat band project I tied, but with more crossings facing outward. There was just enough cord left, after one pass of the knot, to work the remaining paracord under the knots, around the hat one time. Any more cord, and it might get a bit bulky.
I like the knot with the open pattern as it is for a hat band. This also keeps the paracord more easily removable, if it's needed for something else, where a tightly worked knot may have a lot of kinks in the cord, and take considerably longer to unravel.
Tying this is a bit awkward with the branch loops of the hat being sewn in place every inch or two, especially since you can't see the back side of the knot as you do the overs and unders to finish the knot.
It helps to imagine tying the knot around a long cylinder, and once the knot is tied, then bring the ends together at the back of the hat, except with the boonie hat branch loops, you're tying it directly onto the hat. Of course if you want to tie a two bight turks head hat band for a hat that doesn't have branch loops like a boonie hat, just tie one around a long cylinder first, so you have something like this paracord bracelet I tied a couple of years ago. That method would need the knot secured to the hat, and a couple of safety pins would probably work well. If tied on a boonie, the hat band would sit outside the branch loops, like this example...
This was the knot that I'd intended to tie last summer with a previous paracord hat band. At that time, I started making a two bight turks head knot, but after making the first couple of crossings, with the knot being done halfway, I finished with coiling the paracord around the hat, under the knots.