Hmm.
I agree with the idea that a steeper descent angle can be consistent with a lower descent rate (along with 99% of the rest of your post). You just have to fly at the minimum power required speed to make that happen, which is well below best range / best L/D ratio speed.
What I don't see is how, given that you accept L=w cos (descent angle), you can maintain that maximum lift happens anytime other than minimum descent angle.
(Take it to extremes. If you really dirtied up, (say by opening a huge parachute) you'd decrease your descent rate by virtue of massive drag, even though your descent angle would be 90 degrees and lift had disappeared.)
The only thing I can think is that perhaps when you say maximum lift, you mean maximum lift coefficient.
Hmm. Its late. I need more beer.
Regards,
CPB