Watch out for the rh…it should spike and the leaves would be sweating out.
If you’re late into flower it could lead to a problem. U need to vent the space atleast.
I think it’s been said around these parts, that if power is out, open up the tent and turn on a flashlight or let in some daylight during what would normally be “lights on” and seal it back up during lights off. The plants don’t care about light intensity as much as they do the regularity of the cycle.
No they won’t do as well, but they’ll be less likely to herm
You can find some led work type lights at hardware stores that will last about half a day to a day on 2-4 batteries , I’ve resorted to this in the past with success but have a wood stove for heat.