I don't have a DI engine so I can't test this myself, but I've seen people use Amsoil Powerfoam
as the cleaning agent instead. Spray on, soak, drive. No scrubbing or extracting used carb cleaner with a vacuum. There's even a guy out there somewhere who drilled (and then capped) ports in his IM to spray Powerfoam in without having to remove the manifold any more.
Amsoil Powerfoam is made exactly for these kinds of deposits. When you burn it off I'm sure it'll smoke but it will probably cut the time for this job down significantly. The easier this is, the more likely people will do it more often.
Carbon cleaning like this is routine maintenance for a DI engine (in 2012 at least).
is a thread about the guy who modified his intake manifold. Post #2100195 has the details.