Being from Canada we battle with hot hot temps and very cold temps all the time, 58-70 seems very cool. Usually we run evening temps @ 70-78 and day temps @ 79-82 without as much as 10 degrees difference between night and day. IS there any way you can vent/exhaust from indoors? Ie. your rez area or another adjoining room to prevent the very cool temps from entering your room? Ive had to turn my exhaust from 7 mins every 40 mins to 2 mins every 40 in the winter with an extra heater in room to maintain temps. As for mildew, sulphur burners work but I find it tends to leave a sulphury tasting smoke. I use Nova in the first 3 weeks of flower just as a preventative, and then nothing gets sprayed after week 4. Spot spraying helps too, and then pick those affected leaves off after they've been treated. Mold likes cold and damp.