What about the longer hangers that allow the derailleur to clear the larger gears? I don't know anything about the OP's derailleur but I picked up a hanger extension that is suppose to allow my old Shimano derailluer to take a 40t and I think they say the MTB ones can handle 42t (Wolftooth Roadlink or Goatlink). I plan on experimenting to see if I can run a 11-40 with a DA7800 RD. I hate using the front gears, they make the ratios overlap and also more fiddly to shift, I'd rather have all my gears in the back and perfectly sequential (less to setup and tune too). It is an experiment though, we'll see how it goes I may end up not liking it!