Really if you think about it you don't have to close your tent up at all until they start to stink real bad.
If your exhaust fan is able to suck in the sides of your tent then you can open up as many bottom flaps as you want to to allow in fresh air. Some guys if they have some real heat issues will use a powered intake. Course that would give you even more difficulty staying with your humidity goals.
I reviewed our conversation and I decided to give this a go tonight. Should be interesting to see how this works out for me.I actually let my exhaust fan cycle off during hot dry spells to help control my humidity. I have a Titan controller it allows for a high idle a low idle and a completely off setting, still based on my temp settings.
You still want an oscillating fan going, to keep mold spoors from settling.
I like to run my temps in the high 70s with LEDs. Whether or not you close those tent flaps really has to do with how well you can dial in your temperatures and your environment. If it works better with them open then leave them open but if it works better closed you close them. You do want some fresh air coming in but honestly you don't need all that much.