I'm going to cut some mirror up\order it and test it with a partner using 2way radios. Ill let eveyone know how it turns out.

In regards to the cuben, it is pricey. Its about $19 a square meter direct from cubic tech with a minimum order of 9 meters or about $26 per square yard from a fabric supply. I made a rain shell out of the .33 oz stuff using a tape adhesive from 3m and it is very light. Total weight is a little over 1oz and very warm. %100 waterproof and windproof but not breathable, think sauna without incoporating pit zips.

This fabric gets people laughing, my family thinks its funny im making bacpacking gear out of "cuban garbage bags" but it really is great stuff.