You can run your FTP on dynamic IP. Use a Dynamic DNS system. Register a simple FQDN with a provider and install a software to update your IP address frequently. All you need to do is to type in your FQDN when you are elsewhere and you will get your machine. I run VNC with a web interface as well so that I get GUI to my machine where ever I am. You can have the whole setup for free if you are willing to research a little.

Start off your research at www.dyndns.org