A lot of my property is sloped that far, the chickens have zero issues traversing the terrain. If this was my project, I'd likely make the whole setup terraced into the hill to simplify things. Terracing is expensive and a lot of work but that's a steep slope and it will greatly assist with preventing the migration of all bedding materials to the downhill side, which WILL happen once chickens start scratching on it and take out all that grass. For humans to enter a terraced run on the slope, I'd have a side door on each level.