Ah, I had a quick look but I was on mobile - must have missed it.
I reckon you’d be on the right track with the plan you posted. Just, as I say, practice on the right terrain, especially on the long runs. It is a time-suck though, so I hear you on leaving it for another year.
The key differences with marathons, IMO, are that you have to think about pacing much more (it’s easy to pace yourself in a marathon, especially a flat one); food is much more important (so you have to practice eating, find out what you can handle) and pain is more of an issue (especially later on).