imo, dont model a man or a camel or anything. Keep those things out of it. You can convey proportion through ratios of your structures and surroundings - like making the trees smaller and the buildings bigger or something.

Sure a lot of people add things in there for scale, but that makes it just that much more boring and overly explicit if you follow suit. Really good environments don't need that and I'm confident this can be a really good environment.
good luck