Twenty Seventeen custom section – one column layout

I found an answer, but maybe there is a better way using page-templates and applying the change directly.

For now, it’s possible to apply the following in the stylesheet:

body.page-two-column:not(.archive) #primary #panel1 .entry-header{  
  width: 100%;
}
body.page-two-column:not(.archive) #primary #panel1 .entry-content, body.page-two-column #panel1 #comments{
  width: 100%;
}

Altering the #panel number you can hard code the fix onto the respective section.