Custom search results page

Hi there,

I'm using Generatepress and have custom headers on every page (using the page headers technology).
When using search, the results are displayed on a page with no header because there isn't a page to connect this to.

The same accounts for the sidebar, I want to have a different one on the search results page than on other pages. The sidebar can be done using a plugin that i use for other pages as well. But therefore i also have to select the page.

How can i accomplish both things. I basically simply wan't to select a physical page for displaying the search results. If that's possible, the sidebar issue will sort itself out :)

Editing the search.php file, even if it's a child theme is not really an option. Client has to be able to maintain the site.

Thanks in advance!