I don't see 12 buses in Mixbus 32C as any kind of limitation at all.
In <daw of choice> mix and pre-production (i.e. EQ, automation etc.) with your favored workflow. Export tracks/and or stems and import them in Mixbus 32C. Then, as stated above, mix like you are on a real (warm) analog console.
I tend to export live drums as:
1) stereo WAV of toms
2) stereo WAV of OHs
3) mono kick (maybe even Kick in, out, sub)
4) mono snare top and bottom
Those Mixbus 32C tracks now send to one Mixbus 32C drum bus.
MIDI drums such as Superior, AD2, BFD3 can be a different animal and should be handled accordingly by either exporting stems (similar to live drums) or load the VSTi and export/import the actual MIDI used.
5) stereo mix of rhythm guitars
6) stereo mix of solos
7) stereo mix of acoustic guitars
? stereo mix of synths and/or orchestrations
Those Mixbus 32C tracks are sent to one 'music' bus
9) Vocals as needed are sent to one Mixbus 32C bus
10) Bass tracks (dist, clean, DI) are sent to one Mixbus 32C bus
That's only 4 of the 12 fixed Mixbus 32C buses. Vocals could be broken out into lead/bg/gang using 2 more buses, if desired, leaving 6 more buses available.
IIRC Harrison has finally allowed delay compensation on their AUX buses so there is that luxury albeit they are not true buses with the mojo that comes with them.
One man's opinion.
<edit: wrong bus count fixed>