Not arguing.. but I have a domain... mail.DoThis.Com = as an example.
That is the URL used. But it is pointed to the MRS folder...
It has own SSL so technically it is: https://mail.DoThis.com
That is not a Virtual directory, as defined by IIS. You could make it a virtual directory, if you want (I guess that is what you are asking?? - under IIS, to where points to MRS.
But, If you are doing an SSL
Then I am not aware under IIS that you only the virtual directory would have SSL.
As a footnote.... would be curious how your AppPool is set up, if the SM web is ran a virtual directory.
I would think that you have to define it as a Virtual App not as a Virtual Dir