There must be another reason for the heat buildup. Apart from lights and a heater the only other source is your pump. Put your hand on it to see if it's overheating.
As far as all the humidity you're getting I'm not sure what could be going on there. I regularly run my tank at 81 and the tank is behind a display wall so the room isn't that large. My total water volume is a little over 350 gallons and I don't have a problem with humidity.
I just make sure I get good airflow to the room.
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250 gal display tank plumbed directly to my wallet
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