I've had similar humidity battles in my basement, but don't give up on fabric entirely. If you're set on that fantasy vibe, breathable natural fibers ...

Had a similar battle myself when I went with rammed earth walls a couple years back. Inspector acted like I'd suggested building with moon rocks or so...

Totally agree—duct boosters aren't a silver bullet. I've seen folks toss them in hoping to fix deeper issues like undersized returns or leaky ductwork...