I was using the hex dominant with the previous image, but I have also used the Tetrahedral patch conforming method. The below image shows the result.

I worry about the quality of those cells at the very tip of the TE shown here and due to the sharpness of the blade there, there's not much to be done.

Is the previous idea of using another region as the tip clearance region with an interface between this region and the impeller domain not possible then?