I know were a long way from recreating an l5r world but simply changing the way the units look on the campaign map to match the l5r clan counterparts doesn't sound to dificult.
So for clan matchups I was thinking
Ussegi-dragon /forgot spelling
Kinda split on where to put mantis as they do great in comerce and archery like chosekabe and great at sailing like mori so I kinda split their families
doing this all off top of my head so sorry if I forgot anything to important. What I'm dieing to see with this is just an appearance change flag mons, unit colors for each clan and as much of the single player map as possible. Please somone mod this I'm sure lots of l5r fans like me would love this a lot. And I would do whatever I can to help even tho I have no mod tallent as of yet.