The 15" Teleoptar is supposedly the "official" telephoto lens for the Super D Graflex, and yet there is a practical problem in using it. Because of the recessed lens mounting and lens hood in the Super D, when the lens is in place it is almost impossible to either see the f-stop scale or to adjust the diaphragm opening. Doing either requires turning the camera practically upside down, which is inconvenient, to say the least. Does anyone know how this problem was solved by Graflex? A "top hat" lens board, perhaps?

See the Interchanging Lens section of the online RB Graflex Instruction Manual linked in the title line of this section.
Remove the lens board, reclock the lens mount, reinstall the lens board.

Thanks! I looked in the manual, but I cannot see any reference to this problem. (Couldn't find anything in the Graflex-Graphic book either.) I already have the lens oriented in the board so that I can see the index mark on the f-stop scale through one corner of the lens board recess, but to view it I have to turn the camera over, and to adjust it I can only get one finger in between the lens and the recess. Very awkward!

I've used a couple of these 15" on Super D and 5X7 Press. Both lenses had a small milled land with two tapped holes on the aperture dial.

I measured, cut, bent and drilled a suitable piece of aluminum to form an arm to adjust the aperture from the front of the camera. Very simple job actually.

Thanks! That's an excellent idea. A couple of 0-80 screws would be about right.