Looking really good! I use the foam insualtion too & it keeps in way more heat than I expected - really saves on the electric bill. I've never seen a canopy built from it before though. That is a good idea. You might also want to look into a temperature controller. I just bought one from Jehmco & I'm liking the idea of not messing w/ my heaters when the seasons change.
BTW, I keep a vieja community in a 150. Had it up & running for a year now & its been the best tank I've ever kept. I misjudged on the 150 though, they really need the extra room a 180 gives them. An upgrade is in my future.
I don't keep Zonatus as everyone said they are more aggressive, but I have two sp. Coatzacoalcos & they look very similar. Good luck & keep this thread running.