Have you considered letting someone else do it for you? There are both skilled ATMs that could do it, but there are also some professional telescope makers that are willing to build one-offs. New Moon Telescopes comes to mind, as an example.
I have considered it, but haven’t found anyone that I am comfortable asking to do the work. Unless a person has built something very similar recently, its very difficult to predict the outcome with any certainty. It’s a crapshoot especially regarding mechanical aspects such weight, balance, smoothness, and stability (freedom from shakes), which are just as important to me as the optics. It’s easy to clearly and objectively specify a parameter, such as weight, but specifying such things as smoothness and stability is very difficult.
On the other hand, I have methodically gathered and evaluated every component I need for a smaller premium refractor rig except the the OTA itself, and I have evaluated the mount, tripod, DSCs, and all the other accessories working together using an inexpensive Chinese OTA, so the final outcome is much more predictable than would be for a bespoke 6”f8 Dob.
At this point, I just need to select and aquire the OTA. If any component in the final system fails to please for any reason except for limited aperture, it’s easily replaced with another off-the-shelf component.