First, beautiful sketch! You obviously have an eye for natural scale and design. I do have a few points that you might want to take into account. Before that I want to make sure I understand the tank dimensions. Is the tank really 3.2 meters long, as that's about 10.5 feet? If so, you will probably have some trouble with getting good flow throughout the entire tank without a substantial amount of equipment in tank. Second, those rocks (if you keep that scale) will be extremely heavy and require a ton support beneath the tank. Based on the scale of the sketch provided, the large rock on the left of the formation will roughly have a volume of 2.25 cubic feet. Most stone that we use in aquascaping, with dragon stone being an exception, is fairly dense (120-160 lbs/ft^3). So that stone alone would weigh between 270lbs and 360lbs. You are probably looking at 500-600lbs of stone on the right side of the aquarium. The possibility for catastrophe with very large stones near glass is high. I would get an engineer involved in the design of the stand when dealing with that length of tank and that much weight. Also, the forest on the left of the aquarium would be gorgeous if done properly.
I would love to see this tank in real life as it is a beautiful design, but I think it is a little bit ambitious for a new aquascaper. Ambition is a great motivator and I believe that this would be possible with extremely detailed plans and a flawless execution. For the price of just those rocks, you could probably get a full 20gal rimless setup and mess around with different aquascapes as a testing ground for the large tank.
Whatever you decide to do I think your keen eye will produce something to be proud of!