A possibility is to use ssh from your Valley computer to your home computer and set up a tunnel (some tunnels).
So we have two computers: Valley and Home.
On rpi Valley pimatic is installed and listens on port 8080 (for example).
<YOUR_HOME_IP> is the ip-address of your router at home, or in case you have a (free) domain you can also use that domain name.
On computer Valley:
/etc/ssh/sshd_config and add
Restart ssh (daemon):
sudo service ssh
ssh -nNT -R 8080:localhost:8080 -o ServerAliveInterval=30 <YOUR_HOME_IP>
This will create a tunnel from the Valley computer 8080 to the outside world to your <YOUR_HOME_IP>.
ServerAliveInterval=30 will give a ping every 30 seconds to keep the connection alive.
And then from your home computer you use
This should allow it.
There are more HowTo’s but you could read this one or this one or this one.
Or simply google for “reverse ssh tunnel”.
Edit: I did this between 2004 and 2007 when I lived somewhere else and this reminded me of it. I now did it on “theoretical” base and I did not try it.