Best mode for autonomous flight


I’m building autonomous flight quad for indoors missions. So we have PX4FLOW to handle overall position hold (to avoid unnecessary drift) and besides that, we have companion computer what should direct quad by its will.
Initially, i was thinking to use guided_nogps mode and SET_ATTITUDE_TARGET command, but it turns out that this mode does not use OF sensor for the position.
POSHOLD mode uses OF sensor, but I have a feeling that in that mode I can not use attitude targets to control quad. One possible way should be used RC_CHANNELS_OVERRIDE, but it seems bit hackish and unreliable.
So what are your suggestions to solve that problem?