I guess everyone’s different. I had earmolds custom made by ReSound. The receiver openings are centered on the inner face of the mold at least 6 mm up from the lower edge and the receiver ends are recessed at least 4 mm deep inside the molds. With various domes, I frequently had wax in the receiver openings. With the molds, because the receiver openings are higher and the mold keeps the receiver opening from scraping along the side of a canal on insertion, I almost never have any wax debris AT ALL in my receiver openings and have never had them plugged by wax in a month and a half of using them. So one thing to look at might be if there is anything about the design of your mold that encourages plugging of the receiver opening with wax. I have removed my molds with the vent openings, which are on the lower inner face, or other parts of the mold, gobbed up with wax, but never the receiver openings. So on that basis, I’m quite happy with the molds. They’re in-the-outer-canal style of mold about 1.5 cm from outside to inside, going past the first bend in the ear canal.
If it’s just a pressure phenomenon, not an occlusion effect, you might be able to teach yourself to yawn, swallow, or stretch in a way that eliminates any pressure differential between your outer ear and the outside world - think pressure equalization when in a descending airplane.