Shower Waterproofing

I am in the process of waterproofing my shower and have run into a dilema.

I was pre-cutting my Kerdi-corners around the curb and the Kerdi-Line drain and now I have questions. The main Issue is the corner that laps onto the shower drain itself. I cut the corner back to match the top of the shower drain, but that only leaves 1" of Kerdi between the water and the very point of the corner. I have seen Schluter videos that seem to have done the same thing, but with their mantra of "must be a 2" overlap" I am questioning this approah.

I should note that I am planning on using Hydroban over the entire shower floor and up the walls 36" (and also the shower niche). Since I am using HydroBan, I feel I am adding an additional layer of peace of mind. However, if I run that corer out 1" to the edge of the membrane that is attached to the drain, there won't be anywhere for the Hydroban to seal the cornber to the drain membrane. But if I cut the corner lip back 1/4" (white dotted line) then there would be a better edge for the HydroBan to seal where the two membranes overlap -- or that's my theory.

Please advise what you think is the better approach.

Oh, one more thing, on the HydroBan, is that coverage number they give on the package based on one or two coats?

NOTE: I still have to wrap my curb, Kerdi-band the corners and over all screws.

Many thanks,

Roger