For the North-Atlantic crossing, I would definitely recommend against using a "portable" HF. They're cumbersome (and expensive) in light aircraft.
As others have mentioned, the far northern route doesn't require HF, and it's also safer / more comfortable because airports are spaced closer. In a Caravan you'll be able to maintain VHF contact practically the entire time. I always take a satphone along as well.
Atlantic ferry flight routes
The only caveat may be if you are flying a slow airplane in wintertime, it can be advantageous to install a ferry tank & HF radio so you can take the more direct (southern) routes. Otherwise, take the far northern route and enjoy the scenery
