Is there a way I can use bash or apple script to open Safari in Responsive design mode with a screen size set?

I'm looking to send a client to a URL that will be displayed on very particular screen size that isn't a standard horizontal screen. I can use Safari's Responsive design mode to set the exact dimensions (by the way of an ugly slider) and preview what the design will look like.

But clients aren't used to using these tool, so I wondered if I could make a script or action that I can send the client to executes that will put safari into the responsive design mode (with screen size set).

Appreciate any suggestions you might have.