If you are using the new background image option that was added in 9.5, then this background image is tied to 3D view window size, not the material size.
In this case I would just save the preview image and check its size. Then rescale your background image with logo to the same size and it should display correctly.
Of course if you change 3D view size later (e.g. when you use 2D and 3D view side by side) the background may need another adjustment. But if you always save the preview with given 3D view size then it should be fine.