Trouble getting both Qacro and Qstab tuned

This is a complete newbie post, but I could use some help understanding how to tune a quadplane - or to be more accurate, a quad that currently does not possess a wing or tail, but that is running Plane with Q-enabled. I’ve got a bit of experience with Copter, and my usual practice is to tune rate PIDs in acro mode, and then tweak things in other modes as needed. My experience has been that a well tuned acro mode results in a well tuned stab mode. However, with Plane/Q I am not having the same experience.

I first tried flying an Qstab, and it shook pretty badly, I ended up cutting Q_RAT_P gains roughly in half, and then it flew OK in Qstab - not great, but not shaking. Then I switched to Qacro, and it was so squishy that I could barely fly it. Borderline unstable. I then retuned RAT PIDs in Qacro, getting it reasonably snappy, but smooth, but now if I go back to Qsatb, it shakes. I tried playing with Q_ANG_P terms, with values between 2.5 and 6, and they all seem to shake about the smae.

It seems that I can’t resort to the old Copter tuning approach. Is it possible to tune so that both modes fly well, and if so, what’s the procedure? I’ve gone through the Wiki tuning pages, and for the copter part (the only tuning that matters on the current configuration) I’ve tried to follow all the guides for filters and such. It’s a small 6" copter, but a little heavy and lanky compared to a typical 6" racing drone.

Any advice or perhaps pointers to relevant threads that I haven’t found yet, would be most appreciated.