My solution is simpler as shown in the picture, using an L-bracket for a camera. For polar alignment, I adjust declination by extending/shortening a let of the tripod facing to the south, and azimuth by rotating the base loosing the three small screws (I know it is rough alignment).
The L-bracket method was OK, but when I installed a heavier scope MAK127, the bracket part seems too weak to stop the vibration immediately. Then I ordered a more solid mount with fine polar adjustment to the workshop in Japan who accepts orders of specific parts for AZ-GTi and other astronomical equipment. Here is a link of the mount I ordered (on the left).
Edited by Jiro, 01 October 2021 - 02:29 AM.