Hi Ronny my friend:
If you can find a good one (price wise) take the 70-400 II a-mont.
It will serve you excellent in Iceland.
Optically excellent(as good as the Contax) it is much more versatile than any 70-200... and with the LA EA 3 AF works great with the A7RII (but for landscapes you don't need AF anyhow..)
Cheers
Werner