PC
If you look at the
OMDB ADR chart I would guess that it is similar to your situation. [ Runway 12R OMDB] (Note I am not familiar with Dubai just studying the chart).
They would appear to have a small strip of sand separating the taxiway and the start of the associated runway hard surface.
You could add a note in the AIP and maybe the local operators would benefit from a bit of extra information when you implement.
Also procedures should cover what happens when the opposite direction is in use - if the declared distances include that part of the taxiway as a Stopway/Clearway/RESA.
If it was unacceptable to still call it a runway between the taxiway and the displaced threshold then the starter extension option could get around the loss of TODA that would happen if you removed the runway before the threshold. Although this adds to the work required.
If the 8168 figures are OK there is probably a solution. It might even be very simple.