The old Canon FL Tilt shift lens has been converted to work on Nikon Bodies. worked fine because it has an manual aperture ring. the new TSE tilt shift lenses have electronic aperture controlled by the camera body and would be VERY DIFFICULT to convert to nikon.
While the Nikon 85mm T/E is a very nice lens it would be VERY difficult to use UW. The lens is NOT stopped down by the body. to use the lens, you have to focus at wide open, press a button on the lens to stop down, then shoot the photo. OK on a tripod, but pretty difficult UW, IMHO

The Canon TSE lenses have the aperture fully coupled to the camera body, electronically.
one of the justifications for switching to Canon was to use the TSE lens - I own all three (24, 45 and 90 mm) and love them. I frequently use the 90mm to shoot butterflies from different angles and still have the whole critter in focus. with a normal macro lens you can only shoot from a 90 deg angle.
I would love to use UW for macro. the ability to shift the focal plane (Scheimflug movement) would be great for macro. imaging shooting a nudibranch from a 45 deg angle and having the whole body in focus!
the only way I can imagine making it work would be to use the lens in a large dome port with some sort of flexible cable connecting the body controls to the lens knobs.
Rich