Wow Franco thankyou for putting the effort in to try and the photos. I'm not sure if the right picture matches the words but I think I understand. The first picture where you have it pulled somewhat and still the bathtub quite high looks a quite workable solution for many who want to have some gear inside the inner. The subsequent photo with the bathtub practically to the ground looks a bit too far to be a workable system, and I suspect will just accelerate tent wear.
Also the Notch, as I'm only a little taller than you Franco, has a lot of room at the ends which probably is the best answer but having a bit more room at the side too like you show is probably sufficient for most people with similar wish to have more gear inside the inner. I compare my height, my pannier size, and the schematics and I think putting a pannier at head or foot will be the likely best option. The pannier at its widest point is 18" wide - the Notch is 20" at the end so that fits, the pannier's height is 13" and the Notch straight up from where the floor slopes up is 19" tall so there's plenty of height, and the depth, the encroachment into the sleeping area is about 11" so leaving about 73" (108-12-12-11=73) left to sleep in. I'm about 68" so 5" left. So it all works out in the length. Apart from tall people, that is likely what most people will do but to have items overnight close to hand I think also many will stretch the width as you show.
Yes, I was also thinking about SS1. I also looked the Contrail which has a lot of room and is more summer tent. The Notch though has small packed size and to a cyclist that = smaller pannier = more aerodynamic. I'm aspiring to fitting all in 16L which would be incredible. Cyclists less bothered about weight. Backpackers more bothered about weight. Generally, smaller = lighter so very common interests.
So my sleeping mat, I ordered as they were cheap, a Neoair Short which is 47" so to get to 68" just needs a bit of foam like sitmats.
As to packed size, the Notch's volume is 41x9cm = 2.6L. Neoair Small = 1.5L. Stove (Jetboil Sol Ti) = 1.3L, my sleeping bag (PHD Minim 300) is about 5L, so my shelter, sleeping and cooking is 10.4L