Copy a site design to a new site

Site URL: http://www.ogunquitplayhouse.org

Hi - My client has over 400 pages, many of which are full of archived content. I want to essentially split the site into current and archive and have two domains, and have both pages look the same. However, since there are over 400 pages I can't duplicate the site as is. Are there any other ways to duplicate at least the site styles and design? I know I can always repopulate the content on the archived pages, but it would be nice to at least copy the site style and design so I'm sure it looks exactly like the current site, without having to go into all the settings and do this manually. I can charge them, sure, but it also sounds like a lot of work.

Are you looking to split one site into two "sites" with two domains or have two completley seperate sites? I noticed you are using a template from the 7.0 Pacific family. There is a way to have two nav bars and essential make one site look like two.