Cowl vent clean out 1970 duster

Mine was full of mouse nests, but I had the entire air box out of the car and cleaned the vent holes out, then, using a wand, introduced liberal amounts of compressed air through the system, blowing mouse nest and mouse poop all over the place. I had the interior completed gutted when I did this. Makes me itch just thinking about all the nasty crap that came out of there! But, I believe the bag idea would work, though you may need a vent hole in the bag to keep the air flow going. I was amazed at how much crap was in there!!!!