There is no reason to roster Murray as a handcuff (or at all). He has 0 stand alone value with Kamara healthy and if Kamara goes down Murray is a less-talented RB walking into a Teddy Bridgewater led offense.
Fitz is doing very well with Murray, I’m fine trading for him but Fitz is performing as a WR2 so you should be targeting RB2-RB3s. Murray is irrelevant.
Separate question on Penny. I just picked him up in my league because he could have some value if Carson goes down or is punished for fumbling. You don’t need 2QBs on a 1QB team. Drop either Wilson or Kyler for Penny. I’d recommend dropping Wilson. Yes he’s a big name and yes he had a good week but Murray is the better fantasy play since he has a worse defense, more pass attempts, and a better rushing floor. Look to trade Wilson and an RB to upgrade at RB (ex. Wilson and Ingram for Chubb). If you can’t trade Wilson, drop him for best available player on waivers. That might be Penny, that might be someone else.
Chubb owner has Lamar - what about Cam/Brees owner - he has Michel, Duke and Mixon - maybe I can lure Michel or Mixon away for Russ and Ingram. Thoughts? Drop off for me or upgrade?