I'm relatively new to both of these two myself, and it's rare to find Hanbeis as it is. I can do either - I think with Kojuro a canon setting might work better, and with Mitsunari either could work though since I mostly play him post-Hideyoshi rageahol mode, some kind of AU could be interesting. Would you be up for throwing some ideas around in a musebox or PMs?

It took a while for me to actually try picking him up, because it's him, but it turns out that sometimes unbearable monstrosities are a hell of a lot of fun to play. Let me know if you'd like to try something sometime if you get a chance to canon review!