You can do a toon-like shader already in Corona, it just takes a bit of work with a composite map and rendering it as an element, then possibly comping it in Photoshop. Yes, I understand you don't get the cell-shading like a true toon shader but if all you're after is a white image with edges drawn (but not every sub-object edge), you can do that with a comp node with white (or a colour) as the base layer. Then throw a couple of AO and/or Curvature maps on top with the Unoccluded as White, Occluded as black, Colour spread as 1.0 and Calculate from Inside and Outside, set to multiply in the comp node. You can always add a wireframe node in the top or as its own element and using masks, pick and choose which elements in your rendering show the full wireframe (site geometry like roads, sidewalks, driveways, etc. may be a good use for this). If you have trees and grass, you can always omit those from the element itself and they will appear as fully white.
Although I didn't render it, you could go one step further by rendering out a material-overridden version of your view so you have the lighting the way you want, and multiply the fake-toon on top in Photoshop, akin to your original post with the wireframe multiplied.
I get a Toon Shader would be better but you're not without artistic options now.
