So I have almost finished my rewrite of the engine. It's looking pretty good. I also started writing a replacement for SpriteBatch. I'm calling it QuadRenderer for now. It is basically a direct replacement for SpriteBatch except adapted to work with my engine without modification. All that is left to finish it is to implement flipping and texture sorting.
I created a UV space texture to help with creating the standard non-flipped texture coordinates.
You should note that texture space is what you make it. I decided I wanted texture space to map texture space to look like it does above. The actual texture coordinates are like this
So as you can see the texture is automatically flipped for you. Note that this is with a standard orthographic projection where + X axis is to the right and + Y axis is up. Now when you choose your own UV size and UV position it will be mapped to the above image. This makes it easy to create sprite sheets and never worry about why your sprites appear upside down. The same style UV mapping will apply to the SunBurn renderer.