I would probably keep lots of my photos on it, not as a backup but just so that I could have them when I go out.
How would you use these photos while you are out? If it is just to show a portfolio on a low res small screen then you could just downsize the images for the display reducing the storage requirement. If you want the full size original image then why not store them in the cloud or on a server in your house that you can access over the web. It is highly likely that any location requiring the full resolution image will have internet access.
I suppose it depends if your trips will take you past any libraries or internet cafes that you can use to upload things.
Nikkor AF-S DX; 18-105 f/3.5-5.6G VR, 55-300 f/4.5-5.6G VR, 35mm f/1.8G
Speedlight SB-700 http://keystrokesukimages.com