Placement of indoor minisplit unit
If you do not have the space to mount the unit with the required space above you void the warranty! You are purchasing a premium unit and mounting it two close to the ceiling will cause ANY future problems to be on your dime IF the installer will violate the space requirements (some will not).
Placing the unit tight to the bookshelf will block the output also. I would go with what they require because a future real problem may be on you that they would have covered if properly mounted.