it's definitely possible. that's i rolled out my network of sites. i created a single site, set it up pretty much how i wanted it, and then duplicated the *unshared* sql tables with a new prefix, copied the files (edited mainfile.php with the new prefix, site url, site path), and deleted the xoops-generated files that were in templates_c and cache.
i'd like to streamline the process, since that method is still alot of work, but it's better than doing up a site from scratch.
site configs are separate, so you can setup a diff theme for each site. i'm looking to modify the config table tho, so that *every* table can be shared (which is what i need), but with a few settings unique per site (i need to share everything so that the config table can be shared across all sites, but modify it in a way that i can still specify a different sitename, theme, etc, for each site)