Is it possible to change things like Fish's name when you select him at the campsite through custom graphics or is that still not possible? I don't mean the big names, I know those are a sprite of there own, I mean the ones you see over the tiny portraits at the bottom of the screen when you select a mutant.
Indeed. A few people had suggested that commands could have been added for changing game text, but, unfortunately, it is a pretty big effort as for the end result.
Upcoming update will introduce ability to create custom characters - with that you have full control over text/sprites/behaviour for the thing.