: Two ways to do that. First is just an apron
: hanging from the belt. I've seen cosplayers
: do this for pants and a loincloth.
: Second way is what we see here, n.a. s
: ically folding it so it has a thing back.
Indeed. I'd rather have a back flap most of the time, but I've worn some without before, most often like pictured here, with whatever's left hanging in back tucked in somewhere.
I've also done a variant of your first option before, by tying a length of fabric around my waist with the knot in front, and one or both of the loose ends hanging down long enough to serve as a front flap. (Think something like the tied belts [1 2 3] worn by some Xingu-area natives of Brazil.)
Neither are something I've really worn on a trail, though.