80-83 is good, if you don't have a heater then keep the lights on, 60 is a bit cold, 40% is fine, it's not ideal, but it's fine, I'm sure it's higher under your domes, gnats are a huge pain in the ass, the strips work well, but so does letting the soil dry out, the larva will dry out with it, in soil it's also good to let it dry out a bit between waterings, makes the roots look harder for moisture, big roots=big plants... You may want to get a second opinion as to letting the soil dry out as I grow in coco and not soil so I'm giving that advise based on reading not first hand knowledge, I do know that diatamacious earth sprinkled on the tops of your medium will help with the gnat larvae
Happy growing