The humidity in the air is on average 40% in the r...

I agree with @UnkleSkunk. Slow the air moving through the tent if possible. I just did this to slightly increase temperature in my tent. Humidifying a small area like a tent creates big spikes in humidity unless you can find a humidifier that is perfectly sized. Ideally, you could convert the bedroom where the tent is located into a Lung Room. If the Ling Room is not possible, then perhaps find a tiny humidifier such as an ultrasonic fogger for a fountain. You could get a cheap cycle timer if you don't have a humidity controller.

Just a humidifier bro. They make these mini AC's that are actually mini humidifier's that work great for tents.

I had this issue as well. I had to hang 4 towels at the top of my tent above my light to get my RH to around 65 from 45. Every day i would change out towels until i bought a humidifier which helped perfectly. Now im fighting to much humidity.