Comment on SEO Recent Posts WordPress Widget by SEO Dave.
I can tell you what works for me (there’s multiple ways to map domains to one WordPress install) and it’s the WordPress Domain Mapping Plugin: https://wordpress.org/plugins/wordpress-mu-domain-mapping/ (it’s free).
When setup it’s a lot faster to setup new sites. I use the Add Clone Sites for WPMU (batch) plugin https://wordpress.org/plugins/add-cloned-sites-for-wpmu-batch/ for quickly creating new sites (this only works with the WordPress Domain Mapping Plugin).
Search Google for “WordPress Domain Mapping Plugin” and there’s a fair amount of tutorials to use the domain mapping plugin.
I won’t offer support setting this up (other than Stallion specific issues), you’ll need to do your own research: Google is your friend.
Only issue I had with Stallion Responsive is on the Timthumb thumbnails, you have to add the main domain to the Timthumb file as I described in the other comment.
Glad to hear your host sort out the Timthumb issue.