[Theme Twenty Sixteen] How to replace Site Title with an image.

Hi –
I’m building my first WP site on a child of twentysixteen.
The site I’m building is for a non-profit with a very long name. To standardize the look of that name across all it’s collateral we have a logotype image that’s currently 900x75px (yeah – its a really long name) . If you look at the current static version of the site all will be made clear as far as the logotype.

When I try to insert my logotype image as the “Logo” in the Customizer I am required to crop it to a square and this will not do.

I’d like to use my logotype image instead of the Site Title and Tag Line. Can you point me to the steps for doing that please?

Thanks in advance,
Josh