I would leave the smoothing alone and focus on the mask. It and the luminance estimator that you choose will really impact the results…
If you have not seen it check out this video and also many of his other videos are premium DT content…Boris was quite prolific, as of late he has taken a step back but many of his videos are solid gold content for DT users…
These work pretty well…
download and import…they are organized into menu items automatically…