Sorry I did not notice the CA. location.
The US casualty blanket is just like a HD space blanket w/4 grommets, wt. 11oz. color silver/od.
Are the matches dependable enough to keep when you still have a spark lite?
A turkey bag is very strong but open ended. I do not see that as a problem if you have string, no need to tie a knot in the bag.
I would still drop the jetscream and switch it out for a flat whistle.
Do you have any provision for a signal mirror? There are several types of flat mylar mirrors that could work and be cut to size for your kit.