Kanjuro would be so lame and uninteresting...
Yeah at the point anything outside the real Oden would kinda be lame.
We already had a fake Oden stuff with Yamato, their is no a another point to repeat that shit.
Also we see a women who look up for the wounds off the scabbards, in both case neither Hiyori or Toki would teamup with Kanjuro and saying him to do such thing.
In case Onimaru would not work too, I doubt that Hiyori telling Onimaru to transform into Oden to even cut the morals of the Scabbards, they don´t need more moral up, they where already prepared to fight again.
Hiyori asking Onimaru to transform to Oden is like Nami asking Mr.2 to transform into Ace only to joke around with Luffy, imagine how Luffy would feel about such thing, same for Kinemon and co, dude is already crying.
Can you imagine Onimaru doing such things or better, Hiyori allow Onimaru to doo such thing? I think no.