There’s a race this Saturday (March 5) that goes through the route. Here’s all the info:
I also did the route two weeks ago, so if you wanted to download the gpx, feel free.
https://www.strava.com/activities/497522846
You do not have to go as far out as I did to Shi Men to make that turn into the mountain area. The Sakura area are on those streets branching off the No.2 (coastal highway) after Danshui. A lot of them go up and come straight back down.
Good luck!