good all purpose flies or attractors that aren't dependant on seasonal hatches are great additions. My favorite is what we call a green weenie. Looks like a small catapillar, kinda of a "scrambled egg" pattern thats tightly wound.
I agree, plastics aren't really good. They do seem to decay over time and don't tolerte heat ( such as the glove box or cockpit ). The trout tubes and gitzits are soft-plastics (mostly). The Back Country Lures were discussed for a small ultra-light unobtrusive backpacking kit. The author never considered me looking at it for a freshwater survival module.