In today's aerospace world, step changes will be a big detractor to vstabs. They'll need to be able to take a lot of force, especially at the climb/descend phases of flight. I also note that your design has the nose designed down, but the engines (low bypass turbofans, or even turbojets?) pointed at an angle where if the nose angle is at a positive to the horizontal, you could argue that the wash from the engines could disrupt the flow to the T-tail. Given that it's a supersonic aircraft, the exhaust gases are likely to be quite powerful - which you don't want spoiling the airflow under an aerodynamic component.

Have you run the model in a wind test/CFD machine? I'd be interested to see what comes out of it - I'm happy to be proved wrong, but as a general once-over, there's some improvement there matey :)

Also, you're missing over-wing exits and I think that design would need a taildragger wheel, espeically because of the little nub that sticks out at the back of the aircraft. It looks like it makes sense at full power takeoffs, but with a bit of derate and lazy takeoff speeds, you'll be scraping that down the runway so bad you might as well paint it red so you know where you've taken off from.

I know this post will sound like I'm telling you it's shit, but that's not the idea. I like to throw my opinions out and see what comes back - whether it's "ah, yeah you're right" or "listen dude, here's how I school you" - that's how we all learn! Looking forward to your response.