Ahhh, I see! That's an interesting situation!
How much warmer do you think that it would be with lights ON in the daytime? And how much cooler with lights OFF in the nighttime?
With temps getting up to 80 even without lights, that may end up getting too warm depending on your strain?
And with temps falling to 63 even with lights, it would be even cooler without lights and 65 tends to be the coolest I like my tent to get. Granted, cooler temps (that are reasonable) won't kill your plant, just might make it grow slower.
However temps that are too high, as you probably know, can be very detrimental to plant health and can be a perfect set up for pests and diseases.
I don't think I really have a good answer! I would say, if you're going to change the time the lights are on, do it gradually, maybe over the course of a week. That way it wouldn't be so much of a surprise to them. It's the amount of dark hours that keep your plants in the flowering stage, so keep that in mind if you do it gradually.
You mention 'the room' so I'm assuming you're using an entire room for the grow or do you use a tent? If you use a tent, managing the temp/humidity outside of the tent may be able to help switch those temps around to be more appropriate for the on/off cycle.
If it were me, my first goal would be to find a way to get the temps/humidity in check to be aligned with 'day/night' If that wasn't possible, I'd probably keep it the way it is or if I was going to change it, I would do it gradually. I think that the 'low temp' and 'high temp' limits are really just that and not based on lights. It just so happens that it's usually warmer when lights are on so we associate the high temps with 'day' and low temps with 'night'. But I would think that as long as temp/humidity are at the correct levels, it should probably be okay. With lower temps during the 'day', you might just get slower bud development...just thinking out loud!
Sorry to not have a definitive answer, but that's part of the fun of growing! Keep us posted with what you decide and how it goes!
Maybe someone else has some thoughts to share!