After thinking, I think I have a good starting location. After all, the Grineer do have sea units they can deploy (but they won't have them for a while yet).

[hider=Grineer Base Pick]
[img]https://image.prntscr.com/image/OJ2qD_l_SF6DSFUYoYdkng.png[/img]
[/hider]