I've been learning about compound sentences recently while writing a web serial and came across this sentence in one of my chapters (for context, Ralphie is a superhero who has just been told the costume she made for herself looks like a dress, and she's not happy about it because she wanted it to look like a tunic):
'Confused, Ralphie looked down at her costume, and moaned.'
I don't want to omit the second comma, because the pause shows that Ralphie regards her costume for a moment before moaning, but I'm not sure that this is grammatically correct since from what I've learned (or think I've learned), you shouldn't put a comma before an 'and' unless it's the second independent clause of a compound sentence. 'And moaned' has the implied subject of Ralphie, but I don't think that makes it a full-fledged independent clause. So, there's my question: can a compound sentence have an implied second subject in the second clause?