Light deprivation for force flowering

Hi everyone, I live on the east coast of canada. I’m growing mango haze from which I’ve read that it has a flowering time of 9-11 weeks. We dont get 12 hours of darkness here until about the end of september and the first frost usually comes mid October. I’m looking to build a light deprivation tent out of some panda film and PVC to start force flowering now. Question is how would I allow air flow when the plants are covered without letting light in. ( no power available so would have to be natural.) Or if there is any other way to get to harvest safely. (Moving plants inside is also not an option.) Thanks.

hi, i live 2 hour drive east of toronto. my home does not even receive 12 hours of sunlight due to: - a 7 foot fence, 2 very large trees blocking all early morning light + a massive wall of evergreens blocking any + all late day light. i started many fem. seeds from march 14 thru to march 30. i also grabbed 2 clones on may 5. i vegged all plants until i either, ran out of a 1 litre canna terra veg nutes, or june 30 - whichever came first. june 22 was first so i built myself a “box made of black plastic” placed it behind the shed, it receives no direct sunlight, no air circulation, nothing but darkness. the plants go into this “box” every day at 6 pm. they stay there for 5 hours at which time (11 pm) i go out + put the plants in a location that starts with the morning sun hitting the plants around 6:30 - 7:30 am. + its been working out quite well, i must admit. i now have 5 different “start flowering dates” for 5 different strains. there is no air flow thru my “plastic box”. the plants were big enough to withstand the 5 hours locked up in a dark hot humid place. i hope this is helpful

Thanks @growbetter, I’ve actually started building a small shed to put the girls in. I plan on putting them in there all night as I do have alot of residential lighting around at night and is never completely dark. So i think if they’re in there for 12+ hours they will need some ventilation. I’ve think I got it figured out, seen a couple ideas on diy light proof vents online so I’m going to make a go of it.