e-book reader is ideal for trips where you do not know how many books you are going to need. With a reader you do not need to make compromises. You can take 100 books with you.
A friend of mine sells specialized computer equipment to various state agencies, army, police and such rich clients.
Last time I visited his company he showed me a beautiful PDA. A big, ugly looking rugged brick. Green army-like color, metallic ribbed shell covered with rubber, with a clip-on battery that can be attached in heavy gloves, well protected screen, big, metallic connectors protected by a screw-on caps, connector for external supply in a very wide range of voltage. Good resolution for screen.
There are suppliers for such computers.
The only thing I disliked about that PDA was ... yes, you guessed right .... PRICE.
Another option would be something cheap, third hand, something like my dear Cassiopeia A-20, or an old Palm and a good case. Like this: http://www.otterbox.com/products/otterbox/