How to most effectively mixdown multiple stems at once?

Hello

I'm going to need to mixdown many individual tracks for an upcoming project and realize I could probably use a bit of help understanding if I'm using Qtractor effectively. It's probably worth mentioning that all my tracks are routed like so:

1. Track sends MIDI OUT to a unique MIDI Bus
2. MIDI Bus connects to MIDI Input of a plugin hosted inside Carla
3. Plugin's audio outputs connect back to a dedicated Audio Bus inside Qtractor
4. All dedicated Audio Bus outputs route to L/R Inputs of a Audio Bus named MixFinal
4. MixFinal outputs route to Master Input L/R

I'm leaving out details about how I manage Aux Sends in order to blend effects since they eventually just end up in that MixFinal bus.

Using this setup, I've been able to mix down all (or solo'd) tracks to a single track with the following procedure:

1. Mute/solo tracks accordingly
2. Create a new audio "Mixdown" track setting Input to Master and Output to Mixdown (this is the same bus mentioned above).
3. Bring fader of Mixdown track down to 0
4. Arm the track and record

I'll also mention I've gotten into the habit of adding a limiter plugin directly into the Master input (using Qtractor's mixer).

So the above approach has worked very nicely. From there, I'm able to export the resulting clip.

Of course, this is a very tedious process for 2 reasons: 1) I have to play through the entire length of the song and 2) this work needs to be repeated over and over again if I'm creating stems rather than just mixing down the entire song.

I suspect I am not doing this correctly and wonder if someone could school me on how to work more efficiently? That said, I have a sneaking suspicion that any method people might be using to tackle these tasks more effectively assume plugins are hosted within Qtractor itself rather than externally. Maybe I'm wrong to be suspicious though...

Looking forward to any tips. Thanks in advance :)