Humidity, Exhaust and Pests

I have a designated tent I use for veg and lately I've been able to keep the tent around 75 deg F and 60-70% humidity. This is achieved by NOT running the exhaust fan and my plants have been thriving in this environment. Like an idiot, I didn't use any preventative maintenance for pests and I noticed my first signs of spider mites last night.

I sprayed w/ Neem and plugged in my exhaust fan which is now making the environment 65 deg F and 17% RH. All my leaves have drooped due to the conditions.

My plan is to run the exhaust fan for 5min every 60 minutes using an interval timer. Do you guys think that this, along with using Neem and/or other products (recommendations?) is sustainable? Or is the common consensus that you HAVE to run the exhaust 24/7 or you will run into these issues?

I'm afraid a RH of <20% is going to drastically slow down veg growth. I also hate the idea of running a humidifier because the humid air is just going to get sucked out anyway and I need the low RH for my flower tent.

Thoughts?

For smaller spaces, and when humidity is low, I run the exhaust 10-20% duty, 1-2 min run every 10 mins, and run the humidifier at 70-80%. The room where I exhaust the air was never over 50-55% rh, so I don't think it will effect your flower room as much as you think. When the exhaust starts the humidity drops 10-15% maximum, but gets back to optimum in a minute or so after the fan stops.
In grow circulation fans work 100% at the time in my grow, so those won't stop when the exhaust is stopped.
You will find a way to make this work, but careful with those spidermites, it's hard to get rid of them within a grow time and especially in flower or near flowering the plants.

Using too much nitrate nitrogen in a indoor grow will cause a infestation of mites. What kind of fertilizer are you using and how much?