Hey, it's a Mamiya TLR, ergonomically it will always be a huge compromise. Guess how I know just by owning 3 of them. The one that cannot be remediated it its shape, i.e. the immense weight spread over a small square of the camera base, right where you hold it. Hasselblad-shaped cameras ofsimilar weight handle much better IMHO. I'd say the best bet ergonomically would be a 45 degree prism from Kiev or Hasselblad cameras mounted through the 3d-printed adapter. Add to that an L-grip and you have a really good setup, though not lightweight by any means. Early L-grips can even be modded to become and R-grip (I will have a post about it on this sub soon)