|In order to make this work properly, you would need to establish an encrypted VPN tunnel between sites and have a DHCP server running at the other end giving out TCP/IP settings to clients connecting through the tunnel.|
However, since you're sitting somewhere with internet connectivity, it begs the question, "Why would you want to make this harder than it needs to be?" considering you obviously have internet access from where you're physically located.
When it comes to computing in general, and networking specifically, it's always best to apply the KISS principle. Without any info on why you're doing what you're doing (you may have a legitimate reason) all I can tell you is it appears you're making this much more complex than it needs to be.
Perhaps if you explain what it is you're trying to accomplish and what your goals are, we can help you find a better, simpler way to do it.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.