You have a point with the cold.
The plants are 77-80 avg with the room @ 72. So far 72 has not damaged and i do not think it will..

Once again i am not scientist and i am sure maybe 1/2 the things i try have been done. That's why i started using these forums.
I find the red spec. makes my stalks stretch in veg and the blue will keep the Nobe's tighter. I think most know that
So i am trying the red as normal with a t-5 blue more on the outside (Pointing in) to see if i get a reaction with this combination of
Red for primary and the blue as a secondary with the cold air 72 for stress..
This is reversed the other side with the cold on the out of course.

Maybe i am to stoned.... with to much time on my hands.... lol
To me MH is the spring and the summer
MPS is summer...fall harvest.
I go by this because i grew up with only the outside to grow back then.
Now knowing more of the spectrum and trying to add or subtract the spectrum. HPS has less of a light spectrum (I think 2200) and HPS lights may cause distinctive infrared and optical signatures. Now this depends are were you grow as to if it draws insects.(greenhouse). high altitudes do.
So it would be nice to maybe make a strain that can do well... or at least help out others who do... i like making the strain though... that feels good

So maybe i am that kid who use to take the head off of one doll and put on another..
I vegged a tomato to a sativa.....seeds grew up tomato