Don’t worry about the VPD chart, just do what you can. Those numbers are under ideal conditions with all the bells and whistles 
I run a 600w MH/HPS in a 42" reflector. Lights are ~24" from the plants.
Temp can reach 85F and humidity is 40% !
But, I have two 7" fans on the floor of my enclosure (5x5) pointing up at about 30 degrees And an exhaust fan set to come on at 82F.
The idea is the circulating fans on the floor will push cooler air up to the light and when it gets too hot the exhaust fan comes on. Sensor for the exhaust fan is kept at plant top height.
As to humidity, mid winter my rh is anywhere from 20 -30%, with running the humidifier I can’t get it up much more than 50% and I simply got tired of hauling water for it !
Good news, the plants don’t seem to mind and I never have to worry about bud rot
Cheers
Day 14 of 12/12
