On an old site, where i was using PHP, I had a .htaccess in directory /noaccess as follows:
# /noaccess/.htaccess
As far as I know by experience, mod_include follows the limits of the client, so you cannot do what you want with apache directives.
If you want to hide the included files you can disable directory indexes with the Options -Indexes directive on your .htaccess file, though. Also, you can name the included files in a hard to guess way.
My prefered option would be using uuids, you can generate them with online tools or install some utility on your workstation:
itorres@localhost$ uuid
6e8feb48-1a3b-11e0-a0e3-00505624a126
itorres@localhost$ vi noaccess/6e8feb48-1a3b-11e0-a0e3-00505624a126.ssi