The two new cages I built for my ball pythons are insulated and I really think it helps a lot because I'm only using an 11x11" inch heat tape, and it's keeping the temps in the right range sufficiently. I didn't use the aluminum insulation though, I recycled the yellow insulation that comes in the RodentPro boxes. But I didn't insulate just the top, I also insulated the sides and the bottom of the cage. ALL around.
For the daytime, instead of using all of those bulbs that you have, you may want to invest in a PowerSun Mercury Vapor bulb... 100-150 watts, depending on what you get, but it gives TONS of heat and also has UVA and
UVB. Do you use the flourescent as a
UVB source?
As for a nighttime heat source you may also want to try a ceramic heat emitter instead of nighttime bulbs, the
CHEs last much longer.
I don't know if what I suggested will make a difference but it's worth a try.