I was told at RFETS that the lockdown they used in tents was Suave hairspray. They got it in bulk containers. Dries in minutes.
But that was for the bubble suits, so you could cut the workers out with just a respirator on.... they routinely worked in 10k (yes... k) DAC airborne...
Latex paint was the lockdown used on equipment. 2 coats.
Are you doing this in cavity? I would tarp the cavity top with a custom cover, and provide ventilation, treat it as a permit space.
Either way, when you get to cutting - make sure ALL your PPE are fire retardant when doing hot work. Most PAPR hoods aren't.
Good luck.