If you want to use only one hand for all the arrows, I recommend using index finger, middle finger, ring finger, and thumb, all with keys spread out enough to not require any kind of hand contortion. For example, for the right hand, you could set things up something like:
Show Image
(http://i.imgur.com/FTPF0mh.png)
I had never considered a layout like this. I will have to consider it next time I test a new layout.
Perhaps I could leave 'up' and 'down' in more handy positions, and move 'left' and 'right', given that I use them less.
Do you consider this the best position of this type? Depending on the number of keys (and remapping capability) to the right of the spacebar, the pattern could be shifted further to the right 1 key, (possibly) even 2.