3 domain names for one instance of Drupal 8 We are currently developing a website on Drupal 8.

This site will be 3 versions . The difference between each site is minimal :


Different logo
Different colors CSS ( HTML structure remains the same ) .
Some content is filtered according to the domain name . For this, we created a selection field in the content type to know on which domain name the content appears (checkbox  Site A , checkbox Site B,checkbox  Site C. A content may appear in several versions , the choice is multiple)


Our question is : what is the best way manage this type of project with Drupal 8 ? We are aware that this could cause problems at the Drupal cache if we do a simple detection via preprocess to load a particular CSS or content.
I am doing something very similar to migrate some D5, D6 and D7 sites to one D8 site. 
Currently I have this solution:

(1) Have one master domain that serves all content (i.e. proreos.de).

(2) Have some paths (routes) that serve special content for different domains (i.e. /asde/* -> serve content for anwalt-seiten.de/*)

(3) Have ThemeNegotiatiors (ThemeNegotiatorInterface) watching for that special routes to set the 'other' theme (like asde-theme).

(4) Have inverse proxies (apache2 mod_proxy) on the "other" domains that deliver the subcontent from the master domain (i.e. anwalt-seiten.de/index.html -> proreos.de/asde/index.html)

The advantage I hope to have from this approach: 

(a) Have all data in one place (proreos)

(b) Have presentation separated from model (special themes)

(c) Have scalability (by inverse proxies).

But I don't have real experience cause I am still developing. Hope it helps anyway.