This subject comes up fairly often and as it turns out, the choices vary.
I prefer ultralight tackle no matter where I fish. It's perfect for creek fishing around here but none of my 4-5 foot rods collapse or break down, so they never go in the pack. 4 lb. test or the same size in braid (10lb.) is my line choice.

For backpacking or kayaking, I take a break down fly rod that has 5 sections, and a light fly reel, or....and handline. A handline takes some practice but I've always got a bite while drifting with the wind in a kayak (rubber worm or lizard) or tossing a lure across a creek. That's the lightest system I know.
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paul, texas KD5IVP