Reflux baby & sleep training

My son was just diagnosed with reflux at his 4 month appointment and the doctor started him on Zantac and instructed us to keep him upright for 45 mins after all of his feedings. We wanted to sleep train soon and planned to start putting him down drowsy but awake. Not sure how to do this now! After his nighttime bottle, I don’t want to overstimulate him by putting him in his jumperoo or seat, but holding him is almost a guarantee he will fall asleep within those 45 mins. Anyone have any ideas/experience?? Thanks 🙏🏻