I went through a face of combining them in most dosages, and while entertaining and easier than plane DMT it was not as fulfilling to me. Somehow the ketamine makes it super easy but also leaves you feeling somewhat detached from the experience. I tended to forgot these experiences much faster and easier than Dmt, they also did not seem to have the impact (which can be a good thing).
I guess it’s nice enough to have an go at it and I would recommend it since it’s so easy. My preference would be to take the ketamine and then 10 minutes in my dose of DMT.
Although you can manage to dose the DMT right before you enter the hole, I preferred to not take as much of the ketamine. For me the optimal dose would be to get to that stage where you basically have a strong visual daydream. For the the DMT I would say that you can lower the dose by about 1/3
Good luck, and drink plenty of green tea.