You can definitely lose loadsa geo off that plane, probably even halve the amount of tris you got there! The fins (?) themselves have got a lot, you could probably have those as just a quad.
you could lose a ton of tri's if you took out the symetry line, took some edges out of the leg and you could take a ton away from the jet pack's smaller parts (at the top and bottom)
The point of the exercise was to keep the polycount low, so you don't need to add more polygons. You can simply suggest more shape in the texture. I made a paint-over for you to show what I mean: Note that this example texture probably doesn't work well on the actual model, since obviously I couldn't test it out in 3d.…
Always a pleasure seeing your work, Tennis. Have you ever done any streaming or written up how you make your models and plan those layouts? I'd really love to see you in action.