To reiterate... Desert Ghost is NOT a Hypo line. It is a separate mutation. It is possible (and has been done) to have a Hypo Desert Ghost (double recessive).
Most Ghosts (Hypos) are of the Orange or other fruit flavored variety and are generally compatible. For the most part if a breeder is selling a line that is not compatible with Orange Ghost they will say so.
As was said before, in other snakes, Ghost = Hypo + Anery. So Hypo + Axanthic in BPs is called a True Ghost.