A trick to avoid getting a sharp ledge when applying clear. Or any sprayed on paint. It's what is called vignette masking. Instead of applying the masking tape directly to the surface, it is applied above the surface, maybe 1/16th to 1/8 inch from the surface. This requires something under the tape to keep it up away from the surface but it needs to be placed well back from the edge of the tape. Hard to explain in words. Something thicker, that the masking tape can be applied to works well. Like maybe 5 or six pieces of masking tape layered together, and cut into one or 2 inch long pieces.

Anyway, this allows a fine, feathered edge. It may also leave an edge to the paint that is misty with over spray, which can be lightly wet sanded to even it out and blend with the surface. But you have to be careful not to use too heavy a coating or it will puddle under the tape anyway. Many light coats are the key, and that can be difficult with conventional spray cans, which put out a lot of volume. Much easier with an airbrush.