Not sure on value; trying to be realistic.
I think if SJ is sending EK to Edmonton either Broberg or Bouchard is coming back, otherwise it's not worth it.
Campbell and Foegele are not cap dumps per say but their value isn't much. I think Campbell has a chance to be #1 in SJ but he'll probably be an anchor. Foegele is the type of player Grier likes.
Yamamoto is tiny and SJ probably is not that interested with all the smaller players SJ has in the pipeline, but he has decent value and helps balance against Karlsson's cap hit.
Petrov a throw in as a good prospect that doesn't currently count against SPC
Might need another Oiler's prospect, like Lavoie. Savoie is small and I don't see Oilers letting Holloway or Bourgault go.
1st is a must in the deal and may need some of Oiler's 2023 picks if the trade happens at the draft.

I think SJ would go as high as 20% retention but Edmonton would need to add more to the package.

I'd probably do this as SJ if I have buyers for Yamamoto and Bouchard...

Bouchard sure but if there were any buyers for Yamamoto Edmonton would have already traded him. They tried but he's an undersized overpaid arbitration eligible RFA with a 3.2 million qualifying a year from now.