I’m in a similar position to you, I’ve been doing LV plans and supplementing with commute volume.
My thinking has been that the low volume plans have three days of intensity. Obviously this varies based on the plan, but for things like SSBII and general build, that’s 1 vo2 day, 1 sweetspot/threshold day, and a threshold/over-under day.
The mid volume plans have four days of intensity. The three above, plus a longer sweetspot ride. They also have a low intensity recovery/aerobic ride. So based on time and availability, I think adding sweetspot if you’re up for it or recovery if you’re tired would be a good place to start.
However, now that TR supports outside workouts (woop woop), I’m going to start toying with a mid volume plan, where I take some of the workouts outside and do them on my commute. This is easy for the low-intensity aerobic rides, might be challenging for more varied workouts. It’ll be an experiment.