Hi all, the developers don’t have an easy to use solution yet, although defining a “resource template” and restricting a site to searching that is a good start.
Ultimately, what you want to do for now is customize the advanced search form via direct HTML. I am working on this for my site right now (edisondigital.rutgers.edu) and would love to contribute more details in the future, but for now, you should understand that the “theme” is where you can make these edits.
In particular, you can copy this file:
from the base directory of your Omeka installation, and copy it into a theme:
By doing so, you create a “child” or “duplicate” of the default display, which you can safely manipulate. When you break things or mess things up, you can simply delete the file to return back to the default view which is stored outside of the /theme directory.
The details of how to manipulate it, I will try to post later. But you could simply take the source (View Page Source or Inspect mode) from the advanced search page, edit it in a text editor, and then paste into a blank “advanced-search.phtml” located in /themes/theme_name/view/common.
I hope this helps someone.