Dual ply is the answer, which in reality was about as thick as a decent single ply.
Ran one as a rear tyre for long enough that it ended up almost slick, and even put it back on as I’d ripped the sidewall out the tyre I’d replaced it with (mates used to rip the pi$$ about me being too tight to change it, but it was good fun!)
However, for a pump track, grip is low priority. You just want something fast rolling, as if you’re hitting the corners right, you shouldn’t be needing sideways grip.
I did try to run my Larsen tubeless, but I could never get it to seal onto the bead. But in hindsight, I’m not sure how long it would of held up as tubeless, given how little rubber there was on the sidewalls.