Having listened to your advice, I have been playing a P37D for about 5 years, and I’m happy about it except that the saliva gets stuck too often in the reeds. It must be the same problem for everyone.
I went the opposite way in relation to the mouthpiece precisely because of the amount of condensed water that interrupts the reeds. I began to understand why Japanese melodica players often use the flexible tube, in addition to making it possible to play the instrument with both hands. The amount of condensed water decreases drastically and now I only have a problem with the reeds getting stuck if the weather is cold and I play for hours at a time. Most of the condensed water remains in the flexible tube.