I have at work a stainless steel tape. It's 6" w and 1/16th thick. We use on helicopters as patch work. I don't know off hand where you can buy it but I'll ask on monday if you are interested. I used some inside my canopy on the side panels, it's not 100% reflective but does the trick. I don't think it's cheap though. If you don't need much I could see if I could barrow some if you know what I mean.
LMK.
cheers