Head hole is the least of my worries when it comes to rain, I'll just fucking tuck it in with rubber band.
It's the small size of the poncho.
Havent used it in rain as a tent/tarp yet, but yesterday it rained like a motherfucker in Hel and my good old poncho did it's job as always.
By the way - wire-made pins still work on the beach, I worried they wont, one just has to dig deeper to reach the wet sand. And God bless the twine.