I recently ran across a video that answer's your question and I'm sure it solves your problem also. I find the Vegan Ostomy channel on YouTube quite helpful and energizing so I check the content now and then. This edition, entitled "Coloplast SenSura Mio High-Output Ostomy Product Overview" shows some large volume bags. Here is the link:/www.youtube.com/watch?v=vwNBFrfrLvc
Another large volume bag was demonstrated by The Front Butt YouTuber in her video, "Ostomy Ileo Night Pouch Review." This looks like overkill but sometimes it might just fit the bill. The link is here:/www.youtube.com/watch?v=CgjBeyR6qY0
Have a great flight!