just my 0,02 ....
I also happen to use my LMCE storage to download files when travelling, but since I did not like the idea to have an ftp port open to my core I followed a different path.
Basically I use putty to connect via SSH to my core, tunneling through it all the port I want to access.
This way I can remotely and safely access to file system but also I can run a regular orbiter, browse webadmin site, and so on.
As SSH is running by default on your core, you're pretty much done. Just make sure that port 22 on your firewall/router is properly redirected to internal IP of your core.
I use psftp (one of the putty utility, a command line tool ...) to download files, but I guess that you may tunnel port 21 via SSH to your core so you point any ftp client to port 21 of your local host to reach whatever file on your remote NAS.