Hello Jersy,
Anything that is worth doing is worth doing right. When painting with one stage or two stage paints, the paint should wrap around the edges. There's a chance that the paint may start to flake or crack when there's a hard edge from masking an area off. This is usually caused from vibration or slight movement of the joining areas, as would be at the stainless steel beading joint. High probability that if masking the bead, the paint will crack along the bead when the wing is removed later.
You can separate the wings (fenders and quarter panels) enough to remove the beading and leave the wings on.