What about simply tacking plastic sheeting over the fiberglass? That would reduce fiberglass dust in the air significantly. Make that white reflective plastic and kill 2 birds with one stone.

Vacuum well.

Then let a LOUD boombox play up there for a day or 2 while a fan sucks the dusty air out and blows it outside.

An air filter on the intake wouldn't hurt.

I would not hesitate to use that space to do a CFL ScrOG after taking care of the fiberglass dust.