Alright so it is beatable 

The way to do it is as this

use a timer (high recommend, the night is about 7 minutes so it helps)

check on marie every 10 secs at the start to wind her down (use the two clicking sounds as removing one progress)

once you hear the vent, immediately put the paperbag and wait it out , then rewind the puppet when possible

dont flash the middle more than to check if foxbih is there 

now the song and dance

after you flash the fox and use the gun IMMEDIATELY, rewind the puppet for 2-3 clicks while hoping theres no vent crawling or if theres vent crawling rewind twice

the puppet should move every 10-ish seconds (keep this in mind)

so whenever the animatronics attack, hopefully in rhythm, put the paperbag and wait for the vents to clear, then rewind the puppet, IF you have to repair the system, DO IT when vents are clear, and Bjorna is there, when you flash her she'll attack and pull down your monitor while resetting flash/camera continues, which greatly improves time to put the paperbag when somethings is in the vents

so clear vents, rewind, shoot the cowgirl, rewind while shes crying, clear vents, rewind

Marie has 5 stages I think so about 50 seconds give or take, more than enough time to clear vents and maybe even Bjorna and repair, keep this in mind while watching the clock

This took me about 159 tries and RNG is definitely involved if the rhythem does not favor you