Interesting thought.
Makes me remember my old Mantua mallets in HO...
Tried it? No; well sort of, many years ago; but I started with 2 small conventional steamers (Bachmann Prairies) and connected them. A "bit" different than modifying a commercial "mallet"...
It "worked"; but those old B'Mann mechs just weren't up to it.
I dropped the project for the sake of my thinning hairline...
Since all the mass produced articulateds I've seen in N are built more like Mason bogies or "double Fairleys", it would be quite a job. The rear is fairly easy, but the new drive to the front engine and keeping weight on the drivers will take some doing...
I think I can live with the degree of "swing" we have on the front; enough to look good considering most "model" curves.
It does kinda bug me knowing they swing in 3 places they shouldn't, but I don't really see it much, most of the time.
Not enough to risk messing up some fine running locos anyway.
JimR.