The piano desk will have a shelf above it that will cover the rear of the digital piano. The music stand will sit on that shelf which is 33cm deep.
I'm not necessarily after page retainers. I won't need a book light.
I was thinking that I could get whoever I go with to build my piano desk to design me a music stand and build that too. But then it occurred to me that this feels like a problem that should already be solved and I went searching online without much luck.
So before going back to my original plan, I thought I'd checkin here.