Early in my anglo playing, I "solved" this problem on my 30-button Wheatstone-layout by dropping the D# on button 4a-draw to a D natural. (I say "solved" because of course this solution creates other problems down the road. But at the time, I really wanted that D natural on the draw for precisely the reasons discussed here and didn't yet have tunes in my repertoire which might use the D#.)
I've since solved the problem another way, by just switching to the Jeffries-layout Of course, now my playing has advanced to where I periodically want that D#, which is lacking on the 30-button Jeffries-layout... so I just fake it in the lower octave.
Gary, as a fan of John Watcham and of your youtube videos in his style (especially Glorishears), I've been eagerly awaiting this book for some time. I'm delighted to hear of its official publication.