Using a Magic Trackpad 2 upside down
Sebastian, there are some great news for you:

As of today, you can use your Magic Trackpad 2 upside-down with BetterTouchTool:


  BetterTouchTool 1.93 (October, 23, 2016)
  
  
  Fixed some little Sierra issues regarding keyboard shortcuts
  You can now choose whether a normal mouse button should trigger on mouse-down or on mouse-up (click the little gear icon left to the
  mouse button selection)
  You can now repeat an action while a mouse button is pressed (click the little gear icon left to the mouse button selection).
  Added option to mirror the Magic Trackpad orientation for upside-down usage. It's in the advanced trackpad options => General
  


See BetterTouchTool Homepage.