Do you stay in Japan or take it to Canada and modify it there?
Sorry that I did not watch the whole video, but what are the plans? Modify it for offroad or camper van?
For offroading you can lift it a bit. I would not cut into it to make space for huge tyres, the van seems a bit too nice for that.
You have full time 4wd, I think it would be relatively easy to installa transfer case that gives you low-gear and center diff lock (parttime 4x4)
But to be fair, in Japan that would be useless.