Here's a photo of the SAL Pullman Bradley car I recently painted/lettered:
After I applied the Champ decals and used Solv-A-Set to soften/bond the decals to the model, (the Model Flex paint is glossy) I sprayed a coat of gloss over the model, once that dried I sprayed a coat of dull.
I cannot see any edges on the decals. I read on another topic the key is spraying a gloss coat on before the finishing dull coat. Not sure if this is SOP but it worked great on this model.