Again, please do not release fish into the wild, even into the water where they were originally collected. If it gets too big, eat it or just stick it in the freezer to euthanize it, but don't risk destroying the native population with aquarium-borne disease.
It's illegal pretty much everywhere to keep trout caught by any method other than hook-and-line, but I don't see anything unethical about taking a specimen for a tank, especially one of the introduced brown trout.
That said, trout have very particular requirements. It should be fine with crayfish if they are well fed, but you absolutely must have a chiller on the tank, which is expensive, and they like current too. They are very hard if not impossible to feed on flake food too, which complicates their care considerably. Frozen foods should be ok, but live is preferred.
I doubt trout are very interesting fish to keep compared to other, naturally smaller, native fish you could find in other local waters that would be legal to take by net. Try
The North American Native Fishes Association