access seems fine. all patches show "OK".

the installation directory is a sym link, but I assume that's the way it is supposed to be.

all files are correct, but I still get the error.

installing to the deployment directory creates all files and sym links except for a configuration.php file.

This is normal that "configuratoin.php" is not created when you want to create a fresh slave site.

The key element here is the "installation" directory that must be accessible.
You have to check if the "installation" symbolic link is created and if you can access it from the browser. (The answer is probably no).
The directory may exists with another owner or the permission does not allow to see it.
So check the "installation" directory to allow creating the "configuration.php" with the "Joomla installation".

installation sym link is there, pointing correctly, all permissions should make it writeable (I opened it right up, being a test server), and trying the installation dir in a browser just brings me back to the index.php error page of "No configuration file found..."

I'm stumped.

I know this is a permission issue but it is difficult to tell you where.
I have already seen that sometime the "installation" directory exists and the joomla installation seems not be able to see it and I don't know what could case this permission issue.

All I know is that when you have different owner between the master websites and slave site, this may cause such problem.

Perhaps you can try install the "hello world" to discover the owner that is used by your hosting server (probably apaches) that may be different of the "installation" files.

Perhaps the problem is related to the fact the symbolic links are not followed. (apache Options +FollowSymLinks)

I have identified another reason that may cause this problem.

Here it is a procedure to check if you are in a special case.
The problem that I have identified on a hosting server is that the installation/index.php file may not retreive the correct directory path when it is called through a Symbolic Link.
The procedure to detect this case is based on the hello world procedure described in tutorial video 7:

- Copy the "hello.txt" and "hello.php" into the /installation directory.
The hello.txt is just used to allow you checking the URL that you enter in your browser in case where you are not allowed to execute PHP.
- Call the <master domain>/installation/hello.php
Write on a paper the path that is returned by the hello.php
- Repeat the operation with <slave site domain>/installation/hello.php
If the path returned by the slave site URL installation is identical to the one returned by your master website, you may have a problem related on the way your hosting server follow the symbolic links.

To solve such wrong path returned by the installation, it is possible to ask JMS duplicate or restore an installation directory instead of using a Symbolic Link.
You can do that when you create a JMS template in which you enter a specific file and folder tabs setting.
At the line "installation", replace the Symbolic Link action by an "unzip" action in which you provide the path {root}/administrator/components/com_multisites/patches/installation.tar.gz

{root} must be potentially replaced by your master root directory.
This "unzip" action will restore a specific "installation" directory for the slave site.
The result will be that you will have the correct directory path returned by your hosting server and that should allow you creating the fresh slave site.
When the installation is completed, you can remove the "installation" directory created in the slave site (only).

This is very helpful, and I can confirm the hello.php in both slave and master sites show the same path (also that symlinks seem to be functioning), but now that I'm trying to trick into installing, I don't think I get what may happen.

I have found the installation line and changed it to unzip, but this seems only for installing from a template, which would make a full copy of my master site and make the slave site just a copy. Can I set this unzip possibility without using a template?

Also, just for fun, I tried removing the sym link to the installation folder and copied the joomla installation folder myself to see if this fixed it.... there is an EXACT COPY of the joomla installation folder under my slave site folder instead of a symlink.... same "No configuration file found...." error.