Difficult choice to be honest. I already have red and white Corregidor on shelf and I don`t want two exact same paint schemes, also I definitely want red bikes. Decisions... decisions...
My troops are terracotta, in YJ, so I'll probably do dark and light brown with red highlights for mine - that way remotes can swap over without too much trouble, and I can play off my L5R fandom a bit (sparrow clan ftw)
I just used red and white as spot colors on my Keisotsu. You could probable do something without red or white for the Domaru, Tanko, and O-Yoroi, just do a single shoulder pad in red+white to tie the whole force together with the bikes.