Katja, I would use the Elite line. You can always tell the agent that this is where you have been directed repeatedly every time you fly.
I flew CO this week and noticed that a woman in a wheel chair was positioned in front of the line next to the elite line by our boarding gate when the announcement was made for first class boarding. There was no problem, and she actually entered first.
BTW: I was never a Girl Scout, but have usually followed "rules."