Mike, makes total sense.
In fact, our Level 3 plans often have 2-a-day workouts, so this is not unusual. If you are going to double-up and deviate from the Maintenance plan as written, I think it is better to perform the workouts AM and PM as opposed to back-to-back, in general, but back-to-back is fine.
When you move workouts around, you’ve exactly right, we want to avoid two days of high intensity in a row. We’ve spaced those hard workouts out using an easy-hard pattern so that you can fully recover between intense workouts. It’s OK to have two days in a row of high intensity (in fact, in many of our advanced plans there are 4 high intensity workouts a week, so we have to have two in a row), but I would never have 3 in a row.
You might benefit from Chapter 8 of our book 80/20 Triathlon, which covers how to create a custom week of 80/20 training. The principles apply to running as well.