Passive methods to increase humidity

First off, your grow looks great so far and plant is very healthy! Like you already said, potentially keep your medium specifically the top moistened a bit more can certainly increase the RH directly around the plant. Another option that can work for some people (depends on situation) is reduce the exhaust fan speed to allow humid air to build up a bit longer before exhausting out of the tent. Furthermore like people said, you can put bucket of water, or what I like to do, fill a shallow tray with small rock and fill with water. The wet rock allows more surface area for evaporation to occur, meaning water should enter the air quicker and raise RH. I usually top the tray with fresh water once every day or 2. Last option is what I eventually did to reduce my stress about getting the environment perfect.... (not saying i got it nailed by any means, but this strategy gave me more comfort). I too struggle with slightly dry conditions in my 2x2 for veg (35-45%), and encountered the same problem as you regarding a humidifier causing too much humidity (go figure). For me, it came down to purchasing a couple temp/humidity controllers (Inkbird has some nice ones and not too expensive). For veg, a cool-mist humidifier for babies turns on when humidity gets below 50%, and shuts off around 55%... Although the humidifier turns off, the RH continues to slowly rise over 5-10 minutes, before RH gets above 70% causing my exhaust fan to kick on and gradually bring it back to 55% where it shuts off, and repeats when humidity gets low again. Let me know if any of these tips help, and whatever actions you take I wish you the best of success! :D - GreenGrows