Version (d) follows through the implications of the hexatonic cycle and supposes a direct movement from C# major to F major (with an intermediate respelling of the C# triad as Db), and again from F major to A major.
I have worked all of these out in improvisation sessions. Not surprisingly, versions (b) and (c) are the easiest to manage, particularly in the close quarters of an 8-bar strain, but also as an 8-bar contrasting middle leading to a full reprise. Version (d) is not so successful; to make it sound plausible, I had to, as it were, override the close on E by following it with an A major triad -- that additional step on the cycle of fifths made for an uncomplicated move into the D7/b6 dissonance of the reprise. Version (e) sounded quite strange if I attempted to make it compact (fit it in 8 bars), but at least plausible if I stretched it out as a series of tonicizations.
The idea of a close look at chromatic harmonies as an addition to or corrective to linear analyses in the Schenkerian tradition was explored in a convincing way more than twenty years ago by Charles J. Smith (who was reacting to a tendency toward somewhat radically linearized -- and therefore sometimes harmonically obtuse -- readings among the first generation of American post-Schenkerists). More recently, Marianne Kielian Gilbert has given sustained attention to the issue in several articles -- see this post.
References:
Smith, Charles J. "The Functional Extravagance of Chromatic Chords." Music Theory Spectrum 8 (1986): 94-139. See also David Beach, "On Analysis, Beethoven, and Extravagance: A Response to Charles J. Smith," Music Theory Spectrum, 9 (1987): 173-185; and Charles J. Smith, "A Rejoinder to David Beach," Music Theory Spectrum 9 (1987): 186-194.
Kielian Gilbert, Marianne. "Interpreting Schenkerian Prolongation." Music Analysis 22/1-2 (2003): 51-104.
Kielian Gilbert, Marianne. "Inventing a Melody with Harmony: Tonal Potential and Bach’s "Das alte Jahr vergangen ist." Journal of Music Theory 50/1 (2006): 77-101.