Awesome! I had been working on a similar project couldn't figure out the snow on the trees for the life of me! It's great to see how you approached it. The work look great! Thanks for sharing your process.
I believe author would be surprised that it's not american, but soviet bunker :)
Check out a nice Stylized Base Mesh by Dzung Phung Dinh which can be used as a base model or as a reference for different characters.
These are flows I have been continuously working on and refined over cycles of my projects of stylized sexy girl. It will be a perfect base mesh for you to get started or used as a reference to do retopo on your character. The topology and mesh flows have been refined back & forth and tested with deformation.
While they can show a certain level of stylized body features details, they can also maintain a good deformation in relation to joint positions. The Package comes in 3 readable formats ( Maya file, FBX, and OBJ ) with a cleared ID material that indicated the colored topology line. The Models are also unfolded into separated UDIM for easier customization
Here are some deformation and articular joint tests for you see the model in action:
And here is a nice character “Pisciasa” based on this mesh:
You can learn more about the pack here.