If you travel with a firearm you have to check it in a locked case that only you have the key to. NOT a TSA lock. You can of course put anything else of value in your locked case as well.I avoid airline travel like the plague these days, but I don't put anything of value into checked baggage. If I can't carry it on the plane, I would be tempted to ship it to myself. Too much stuff in checked baggage grows legs and walks.
Your second recommendation is brilliant. And an excuse to invest in another Pelican case or two!
Cases with firearms in them magically never get "lost".