One of my colleagues has done some investigations into the effect of density on multirotor performance before. I don't have time to run the model for this spec

One of my colleagues has done some investigations into the effect of density on multirotor performance before. I don't have time to run the model for this specific case, but from a similar case with a lower air density of 0.71kg/m^2 (40c at 4km altitude) a simple quad uses ~20% more power in a stationary hover than at sea level. Interestingly at high flight speeds (15-20m/s) you could actually start to see power savings at this altitude, as the parasitic drag of the vehicle body is reduced.