Forget the mirrors, they don't actually reflect light well (odd as that may seem). Paint everything flat white and keep it clean, cheap and easy.
Coke can reflectors sound like a good plan though. Try and get a picture/guide to building them if they work out well. I'm sure it will be useful for the new, small scale stealth growers and seed/clone boxers as well.
Continued good luck. Sounds like your having fun, that's what we like to hear, enjoy your gardening!!
SS