This is not a problem I thought about or expected to deal with, primarily because I plan to take a different, more grand tactical if you will, approach to the game. I never planned on requiring ships to move every turn. Instead of the standard Song of Blades and Heroes movement, I planned to create a gridded board, something like the picture below (created in PowerPoint). If a ship fails to activate, I'll assume that it is slowly cruising in its current zone.
|A sample gridded space battle board.|
Each side features a cruiser, 2 escorts, and a squadron of fighters (represented by 1 ship)
The idea for this grid comes from the range bands featured in Minden Games' battleship game called Salvo! (note that Minden also produces Eindekker). Panzer 8 emulated the range bands for their WW2 naval rules, (You may notice that I envision starship battles as WW2 in space. It may not be accurate or plausible but I don't really care about that). I'm toying with further dividing the board into left, center, and right zones.
My plan will avoid the "running into planets" issue. It may be too abstract for some, but I prefer simpler, somewhat abstract systems. I think it will work, although I'll probably to run into other, currently unexpected issues.