I saw some options for the size in one of the settings files, so that should be doable. But what I really wanted was to make the blue oceans permanent (the color you see when you hover over it, instead of the ugly default brown oceans) and did not find a way to do that.
(one of the three .INI files at this location: Documents\My Games\Sid Meier's Civilization Beyond Earth\) forget which one.