.......................... If you actually built it up like that it'd be way tail heavy and wouldn't have enough wing to lift the extra weight without an enormous wing loading, plus without the draught from the prop going over the fuselage the standard vertical & rudder would be fairly useless once the tail wheel left the ground.
Tail heavy? With twice as many engines in front of the CG, I would think it would be NOSE heavy. Extending the tail would go a long way towards balancing it out, and would add much needed stability, but I'm thinking the tail surfaces would STILL need to be enlarged some, and adding a little more wing area wouldn't hurt either. Maybe somethinh like adding FULL wing panels aoutboard of the engines, with constant chord 'plugs' between engines and fuselage. And then there's the landing gear: even the twin Mustangs had to come up with a differnt main gear arangement than the P-51.
I am familiar with the story of this aircraft, have never seen anything (drawings, pics, or otherwise) of it other than the photo that you posted. As stated: it WAS a mockup. And altho it may have been seriously considered at some time: I'm sure the 'designers' quickly realized that a LOT of modifications would be needed to make it flyable.