I asked my brother the firefighter that question after he finished his wildland training. He laughed- not the "of course" laugh, or the "are you joking" laugh, more of the "if they issued us toe tags it would be bad for morale" laugh.
For the size, the Thermolite bivy from AMK is a better buy. Use the proper tool and you'll be happy. The fire shelter was designed to give you a chance at surviving a fast moving fire. The Thermolite was designed to be an emergency sleeping bag.
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-IronRaven
When a man dare not speak without malice for fear of giving insult, that is when truth starts to die. Truth is the truest freedom.