Agreed with the first two replies. If you know they're all going to your backhand, anticipate and run around to set up your forehand. It should be easy because you know the ball's going to go in that general vicinity anyway.
Once you start leaning to your right to try and run around, he may make an adjustment and sometimes hit to your forehand side to keep you off balance, and the game now opens up into him hitting to your backhand like ~75% of the time but also going to your forehand 25% of the time so you can't always run around. Now you're in a chess match but you're actively getting your forehand involved to hopefully take control of the point.