I have a vaulted ceiling which meets a flat second floor ceiling in my loft area. Just beneath this joint is the railing. The tape has begun peeling and separating almost the entire length, roughly twenty feet long. Once I removed the old tape, etc., I will mud and tape and so on. My question is how can I keep the joint line straight for such a long distance. I will be leaning somewhat over the railing as I stand on the ladder, so this will be precarious, to say the least. Once the tape is set, is it best to try to do both sides all the way, or just one side, let it dry, then do the other? I can mud and sand to make it look ok, not professional, but the idea of a wavy seam would make me crazy. Help!