I've tried it on several masks, all size medium. I do have a large Quattro somewhere that I can try it on. Maybe the extra thickness requires a larger size?
Last night I tried shoving the gel inside the mask to make sure there was an inch margin on the inside. As you said, the gel tries to go back to it's original shape and it felt like it was crawling on my skin before the air finally busted through. If I poked it from the outside, it would stop leaking for a few seconds and then the crawling sensation and the leak would pop through, again. On prior nights the gel came completely over my eyes, a very strange sensation. Last night with the extra poked inside, the edge of the gel was hitting me square in my eyes, making it very uncomfortable. I haven't trimmed it back for my eyes as I'm afraid to cut it too much and not have enough margin. I would rather have it come completely over my eyes than to end in my eyes.
I'm certainly open to suggestions. I want this to work.