Sunlight reflectivity of metal roofing

I have a home with a finished basement story set into a hillside such that the rear of the homes basement is walk out access.The home also has a wrap around deck even with the 1st floor level,meaning the rear 6 ft wide deck is overhead when walking through the rear door downstairs.The basement den has an approx 20" X 30" double hung window that gets almost no light into the den because of that overhead deck that extends 6 ft off the rear of the home.I want to hang, off that deck, a reflective material that will direct sunlight under the deck and through the window into the den.Will a metal roofing material such as corrugated aluminum accomplish that goal? I've priced tempered mirror glass and mirror acrylic and both are, of course, quite expensive.So I'm wondering whether the right metal roofing material would accomplish the same task at lower cost while withstanding the weather better in the process.

Sorry if using the word "hang" caused any confusion.I'll come off the decks outside ledger board at an approx 45 degree down angle with 2 short lengths of 2X4 and suspended between them a frame with the reflective material in the frame such that that frame can be tilted to match up with the sunlight and then tightened down.The rear of the home faces south so such a "contraption" should track the arcing sun fairly well.I've already held a mirror outside at the angle I'll need and that worked amazingly well.My question basically involves how much less reflective a piece of corrugated metal roofing would be compared to mirror glass.I could use aluminum sheet but I'm told that will oxidize over time and deteriorate due to the oxidation.Long story short I'm sure the idea will work.The question is what material to use for reflecting daylight at that window.