Hi Jordan
It looks good so far.
However, I have a few nickpicks. If you are depicting loose sand/earth in a forest the tank obstacles should be sunk into the ground a bit. However, if it is a road or similar you should leave them as they are.
I assume you will paint the crater in lighter colours to fit the sand/earth area?
The sand is not too bright if you are making a beach, but if you are going for a forested area you might want to give it a wash or two.
It looks good and is a good idea and tells an effective story when finished I am sure. Where did you get the display case? Did you make it yourself?