Re: So you're commissioned to write an actual Star Trek book...
I would pitch a series of adaptations/novelizations of the Phase II
scripts that were written back in the late 1970's for the series that wasn't made. I would start with the two-part episode Kitumba
to kick it off.
Either do them with Decker/Ilia/Xon in place as an "alternate history" of Trek (my preference), or tweak them to reflect the actual canon/continuity we saw on-screen.
USS Galileo Galilei, NCC-8888
Starbase 31, Daran V
Prima Inter Pares