I could be wrong, but could it not be done using some kind of instanceing? That way you’d have the best of both worlds; the primary ship is stationary because all of the primary ship stuff is actually in an instance, but the instance of the primary ship is parented to an actual moving ship exterior. If the player were to jump out, they’d effectively leave the ship instance and have to be calculated normally. I know people did some pretty crazy things with the instancing in the source engine when Portal 2 introduced that.
Perhaps you could do it by cleverly switching between a stationary ship and an actual moving one? I mean, say the player walks into the cockpit or bridge to fly the ship. When the door behind the player closes, you could switch the player into an actual dynamic ship which hasn’t got to worry about actually rendering the interior at all; the only physics objects to calculate are the ship and the player. Then when the player walks back into the rest of the ship, you put them into a fake ship. Hell, the old (pretty terrible) source engine method was to use Render Targets to make fake windows in the stationary ship. The cameras would be attached to where the windows would be on the real ship, and then you’d have a TV screen showing the exterior view instead of a window. That could be a more viable way to “cheat” this kind of thing.
Sorry for all of the imprecise “ideas guy” non-technical speak, I’m still pretty inexperienced with UE4.