Double harmonic scale, key signature?

A piece in the D double harmonic scale, is the key signature writing down B flat(compare to d minor key signature), B flat and E flat(compare to g minor key signature), or B flat E flat and F sharp?

Duble harmonic scale from D is:    

There are no standard key signatures for all these scales.

If your composition remains constant, you can put all the accidentals in the key signatura.

If not, I would prefer not and write every accidental when it occurs during the work.

The Russians (Rimskiy, Rachmaninoff, etc) tended to use the normal key signature of the major scale that starts on the tonic. You have either this option, or dispense with key signatures entirely in this case (what I'd personally do at the present day).

If you were to use key signatures, I don't using signatures with flats, only use the D major signature. You may save ink using a 2-flat signature, but it'll be misleading for many performers (respecting the fact that the tonic chord is major is important). Also, "made-up" signatures combining sharps and flats are something 99% of the performers will hate.