Hi @nkoppul1,
To find more appropriate solution we need to know more requirements about MSM support, dynamic components, integration with 3rd parties etc.
Based on provided info I can suggest few options:
Option #1 - site root is a page
You are going to have N brands that will reuse same components (without proxying). You can create /content/mastersite/brandA, /content/mastersite/brandB, ... /content/mastersite/brandY. Having some rewrite map you can pass through requests to the specific brand page root. Example:
Rewrite Map entries:
www.brand-a.com /content/mastersite/brandA
www.brand-b.com /content/mastersite/brandB
Your CDN should pass some header like X-Forwarded-Host with certain brand host and it will help you to do rewriting to the corresponding site root.
This approach will require correct infrastructure and dispatcher setup even on dev and stage environments. However, using this approach you can build separate brands as a page of some master site. In addition, CA config should help to create brand-specific configurations.
Option #2 - same content for all brands with dynamic parts. But I'd not suggest this approach. It will be hard to maintain and extend it in future.
You can setup one site /content/mainsite and build components that will include brand-specific site parts based on some criteria (X-Forwarded-Host).