Hello!
You can successfully rig any direction inside the same skeleton if you want:
A series of streams where this character was rigged showing the complete process can be found here, along with the downloadable project: Spine: Twitch
The first video showing the rigging is here:
I suggest navigating the videos using the chapters in the video descriptions, as they can be quite long given that they showed rigging live.
The technique revolves around reusing the same bones for the different directions, storing then in a turnaround animation, and having in setup pose a neutral pose.
If you only have isometric directions for your character, you could rig the front first, which can be rich in details, and then reuse what bones you can for the back of the character.
