if the room gets so hot paint fumes are a problem your plants will be dead from the heat anyway.you can add mylar but as it gets dirty you lose a lot of light.the plain white is cleanable and reflects light good.
i wanted you to get 4 -- two gallon buckets but i was not sure how tall you wanted your plants to get? you can cut the tops off any 2 liter soda bottle and paint them white and make them your buckets for a while.
