Ok, so I figured out how to do this ... I think I was actually over-complicating it in my mind, so maybe others figured this out, but just in case I thought I'd put the exact steps down for anyone else trying to do the same thing who maybe is making it harder than it needs to be (like me!).
1. Setup master site
If you're like me, you might already have a master/original site setup. Either way, once you have a master site ready, install JMS Multi site on that site (directions in videos and manual explain this process adequately). For this example, let's say I called my master site "IceCreamSite" w/ domain name "icecreamsite.com". (BTW, this isn't real
)
2. Create new template.
a. Enter ID. (In my case I entered "IceCreamSlaveTemplate")
b. Select Template Site = "< Master Site >".
c. Check the box called "Share the whole site".
d. Go to "Folders and Files" tab and make desired selections. (In my case I left everything with the default selections except '.htaccess' and 'robots.txt' - I set both of these to "Copy the folder or file")
e. I left the "Sharing" tab as-is
f. Save.
3. Create the slave site.
a. Enter Site ID. (In my case I entered "IceCreamSlaveSite")
b. Enter your list of domain names. (In my case I entered "
www.icecreamsite2.com" and "icecreamsite2.com")
c. Select the template you created in step #2 above from the Templates dropdown list. (In my case I selected "IceCreamSlaveSiteTemplate")
d. Check the box called "Share the whole site".
*e. Deployed Directory. Now in my case my hosting plan forces me to point all domains to my root directory, so I didn't need to enter a deployed directory. However, if you set up the domain that you are using for your slave site (in my example it was icecreamsite2.com) so that it goes to a subdirectory/folder in your hosting account, then you would need to enter the path to that directory in this Deployed Directory field. (So, in my case, had I been able to point icecreamsite2.com to a subdirectory in my hosting account called "icecreamsite2", then my Deployed Directory might have been something like "/icecreamsitemain/root/icecreamsite2")
f. Save.
That's it. After the slave site has been saved, you should now be able to go to it in your browser (in my case,
www.icecreamsite2.com) and it should basically be an exact mirror of your main/master site. It's sharing the same content/database,etc. So any changes made in the adminstration area of the master site should be reflected on the slave site as well.