I would turn your exhaust fan down a bit.. maybe keep some of that humidity in the tent.. or move the humidifier outside and suck the humid air in.
Other things you can do but don't work too well and could cause some other issues.. but mist the walls, add a bucket of water.. sometimes a fan blowing on a wet towel could work too.
Also, i would recommend 2 thermostats and ways to measure humidity.. this way you will know if the readings you get are right... sometimes cheap thermostats can be wonky.