I think a lot of your issues with having to use Cartesian box region refinements will disappear if you use my [Feature refinement trick at this topic link]( What to do if geometry does not appear in your Hex-dominant parametric algorithm mesh - try the Feature Trick)…
Also check out my Cybertruck meshing here… It may give you clues too… I did not use any Cartesian region boxes in that mesh since I used the Feature refinement trick…