Being in the SE USA, I too must deal with summer temps. I recently converted a cooltube hps system over to a mix of led and cobs, primarily because of heat. This will be my first summer under the new setup.
My intake is filtered from a crawlspace underneath via 4" centrifugal fan on variable control. Exhaust is through a flue via another 4" setup.
I still run lights at night to make use of cooler outside air which helps maintain the tent temps.
The only time I'm concerned with humidity is winter when to have to run a humidifier.
I hope its gonna be easier to keep temps below 85f which was difficult previously.
I've kinda set that goal as somewhere the past few years, I read that trics form slower above 85...
Air exchange/ventilation should help offset temps so that higher temps may not harm as much...at least that's what I like to believe, cause I don't want to add ac to my lil tent!