Coat hangers heat up and break, and they don't last as long, metal fatigue. Piano wire, or other slim, rugged and semi stiff wires work, some offshore fishing leads. My best is Mig welding wire. Pulling always works better, you can feel mistakes or challenges. A good permanent marker is a must. You can try talking to a production or veteran spliced to get their standard measurements. Another good tool is a set of small picks and awls. sharp scissors and masking tape.After pushing the wire loop through the core to ready to pull back, hook the other end up to a small ratchet strap to extract the tail. I had an eye in the floor specifically for pulling dbl braid eyes together. Sorry for rambling/bouncing around, new here and figuring out navigation.
I have all the stuff you're listing except the piano wire or mig wire. I still don't understand how you're attaching the core to it, to pull it through. Got a sketch or photo?