I think more patterns with empty tracks is definitely the simplest. I’d copy/paste the full patterns on the last pattern slots just in case.
Let’s think about how would you arrange your songs with a midi processor :
Would you set OT some midi tracks with mutes messages and mute them with Arranger?
Do you use midi tracks for other purposes?
You’d need one midi track per mute / status change. You’d propably need several OT patterns, depending on available midi tracks, number of different mute status you’d want.
There are many midi processors, I have some.
Midi Processors with Octatrack
Bomebox I don’t have seems very interesting. You can try Bomebox possibilities with its software trial. Midiox soft can be used as midi processor too I think.
Event Processor is limited to 10 events, not enough, (vs 32 for Plus version).