I've flown with Southwest several times since being diagnosed, and besides some hives, have never had problems. I always mark peanut dust allergy when I book the reservation. When I check in I remind them and am given a peanut dust allergy slip to give the flight attendants. I have always made it through security with no questions about the epi pens, clorox wipes, inhalers and nebulizer that come with me. I have had some questions about hydrocortosone cream, at which point I said medication and showed my arms which were already reacting to something. They stopped questioning me. At the gate, ask to pre-board to wipe down the seats. I have always been given this without question, and have even had it recommended to me by the agent checking me in. Once on board, I have had no problems cleaning seats, and have never had them pass out peanuts on the flight. One time they even verified that I was fine with a may contain being passed out. About 50% of the time the flight attendants have OFFERED to make a please refrain from eating nuts on the flight announcement. Also, the last two times I have flow, the flight attendants have asked me about if I had epi pens with me and where they were in case of an emergency and I needed help administering them.
Just my experience!