Speaking from our experience cruising over the last 2 years... I think the best answer is simply not to worry too much about this.
We lived and traveled (while often working remotely) by land for several years in the US and constantly worked/struggled to find data.
Now, 2 years island hopping in the Caribbean
and the very general answer is that (while we've still had to work
at it and figure it out in different places), its generally been far easier than back in the states. Yes, seriously.
Do I think that will change as we move into the pacific and other regions, probably...
but I also thought it would be worse/harder here than it has turned out... so we don't spend too much time worrying about it and assume we'll figure it out when we get there.