This was exactly why I wnated to understand more about your environment.
If you were to place ARR in front of your 2 content servers, you have a couple of options:
- You would just use one IP on ARR and bind 7 domain names to the same IP. Based on the host header, you can route them to different server farm (7 of them - one each).
- Alternatively, you can have the same 7 VIPs on ARR - and route them to 7 different server farms explicitly based on the site.
In both cases, you will need 7 server farms.
The most invasive change would be to use host name binding on your content servers (as opposed to using dedicated IPs) - but I am assuming that you have the business needs for assigning them dedicated IPs. As long as you are usding dedicated IPs, you will need to create 7 server farms and use the URL rewrite rule on ARR to route to the 7 server farms as appropriate.