Sometimes I work with java teams, what mainly means that they cannot handle real 3d, so the way to work is pre-rendering. Yo do your own model without any concern about the polycount, the only thing that counts is to have a well set camera oriented as an isometric view and be faithful to the concept. Having an unique point of view gives you the chance to add some tricks in the model and not worrying much about what is behind.
This is rendered using V-ray and using different render elements. They are mixed in photoshop and ready for the over-painting.