Elliott,
For pitching a demo to a publisher the rules are very, very simple.
Keep it as simple as you can.
A two track acoustic and vocal is sometimes all that is needed.
They don't want to hear your production, just the song. They will produce it in their heads. Over-produced demos are dangerous territory.
Plan B is to go into a studio and come out sounding exactly like Morgan Wallen but that is 5 grand.
If you can't do that it is safer to have a perfect sounding guitar (or piano) and a pro vocal.
And a song that gives everyone goosebumps or makes them say "hot damn."
They can take it from there.