I largely agree with most of what you have written in the entries. In short, line diameter introduces drag. Drape introduces drag. No argument there.
How I overcome drag is to introduce more drag on my fly. Futsu style flies or palmered stiff hackle will do this. The fly has drag that overcomes tippet and even casting line drag. With my spiderwire lines, they are light enough that they dont introduce too much drape. But even with furled lines, I doubt the weight difference is that much of a big deal.
For straight line presentations, I suspect you will dig this general fly pattern. It has more tactile contact than a bead, even unweighed. If the current is strong, the rod can be bent slightly because of the resistance.
There are more detailed notes here.
In terms of deep pool and heavy flies. I tend to max out to lightly weighed flies. If I use beads they are small and the fly is sometimes balanced with some copper wire. Futsu is really the ticket to deep presentations for me. If you have not tried it, you will laugh at how much resistence it can create…and it tends not to find snags like metal will. It delivers naturally because the current suspends it, it also drags it down deep. With really deep pools Sometimes my running line will helix in the different currents. It requires patience for the fly to make its way, riding the currents often to where the fish are holding. If you can see your running line at depth, you can often see the subtle takes.