Congrats on getting the humidifier. It's such an underrated investment. I only run mine when the lights are on. Without those CFLs burning off all the moisture, RH levels should be okay for you. 50% RH at 76* is nice.
Where are you exhausting to? If the exhaust air is being recirculated through the intake it's going to keep your temps high. Fill us in on the exhaust setup and get us some pics if you can.
If you're growing organic you should check out Subcool's Super Soil thread.
https://www.rollitup.org/subcools-old-school-organics/44686-subcools-super-soil.html If you want organic I would do something like that on a drip. You should check out Subcool's write-ups, they're full of great ideas.
With CFLs you'll have to keep your plants short unless you can surround the plants with side-lighting. I would suggest sea of green in like 1/2 gallon bags on a drip.