I like to use the Trial Character function to create future characters. Aside from testing out their combat I also use it to see what they will look like in game. Right now I just delete the character, adjust something, and remake which is not bad. If we had unlimited use of the in-game appearance change in the trial space it would make things faster and smoother. 

Here are some other suggestions:

1) Add a special stable for the trial space with horses and horse gear. It would allow us to check how severely a character will float above their mount.

2) Honor outfits and/or access to game armor/gear. It would let us see what our character will look like in those armors.

3) Merv's Palette. To experiment with.

Of course make it so that you can't take any of this outside the trial space or sell them!