Reflective tape is a lot like foil and it works fine. I saw a post on a competing forum where someone made a Rubbermaid+CFL tank. He used that foil tape made for sealing residential HVAC systems/ducting and it worked great. It's probably the most durable option out there.
How many watts does this setup use? (true watts, not equivalent) If electricity is running you about $0.10 per kilowatt-hour and you're pulling 250 watts of power, the increase will be approx:
$18/mo if on 24 hrs a day
$13.50/mo for 18/6
$9/mo for 12/12
Well I have the 6 26 watts, thats like 156 total and a computer fan, so..eh?