I also used the pro boolean tool to cut away the tie fighter hatch, I used this instead of the boolean tool because I had the same issues I keep having where its cut away the polygons as oppose to indenting into the model.
Not entirely sure what the difference is between the two tools just yet but it worked well!
After a quick search on the internet I also found a picture of the back.
Overall using the schematic images surrounding the model and the back image of the tie fighter I think I managed to recreate the back portion very well. There is still missing details but I'll come back to this once the main shape is complete.