I love working thru minutiae, questions and feedback are always welcome here.
In my experience, stationary is an awesome way (at least for me) do to reverse lunges.
When I try to do rear leg elevated work getting balanced and hopping with 135-315 on my back felt really awkward. I never saw enough benefit to justify the potential consequence of falling on my face.
I'm all for some really long lunge challenges. My record is 1 mile with bodyweight, and a quarter mile with a couple of 50's. No idea on time though, just tried to keep lunging until it was over.