Unfortunately, @richards method is the only way at this time to add code at the end of the HTML in BSS.
I requested this feature many months ago here (even created an image showing a potential interface, which seems quite simple to me.)
But so far, the devs have only given us the ability to add at the beginning or end of the head section. It’s kind of frustrating because the location of added code affects how your page scores on Google’s Page Speed Insights.
Guess I’ll give the post another bump.