For the Temps - The only way you are going to get consistent & controlled temps 24 hours a day is with a thermostat. Stats adjust the cage heating so that it is not effected by ambient rooms temps. Since you really can't use a t-stat with lighting, that means switching to belly heat (IMO flexwatt is best, not the pet store junk) which will also helps with your humidity.

For your humidity - The lights are killing you. They literally burn the moisture out of the air in your tank. If you were to switch to an all UTH solution (I prefer heat tape) the rising warm air will hold moisture much better. And since you won't have all of that junk on top of your screen, you can go to home depot (or DIY home improvement store of your choice) and get a piece of plexi glass cut to fit inside the ridge of your screen top. For ventilation, you can drill a bunch of holes in the plexi, or actually have it cut about an inch short of your screen on all sides and just fasten it to the center of your screen top.

Just some ideas if you decide to make changes.

Hope this helps.

-adam