I agree with using mylar. About that glossy white you painted on the walls. Painting white is good, but gloss/semi-gloss can create hotspots on your plants. You want to paint that flat white. But still consider mylar.

And I agree with the tell no one rule. Keep it secret keep it safe. LoL now I feel like a fucking nerd.... anyways good luck with the rest of it. At the very least it's a learning experience like you pointed out.