- it is much more important for you to HAVE those BMs than to mess up your "clock" and BM consistency !!!! When you "need to go" - you go ! There are multiple lavatories on airplane and do not worry about "people waiting" for you to get out of lavatory (which is what I always "worry about" - idiot LMAO) . I have strong aversion to public bathrooms and I thought I would NEVER be able to do it in a plane and guess what - I did it 
LOL. I brought Balneol cream with me in a lavatory and used it on TP for cleaning and it worked great. It gently cleanse the area and also soothes the butt so it was a life-saver for me : ))). I would be very afraid to use enema of any kind
- my butt was soooo super sensitive when I had a fissure - even baby glycerin suppository would irritate me Of course - stay hydrated to the max !!!!!!!
Wishing you great flight and super successful and uneventful pooping on a plane
PS: JUST SAW THIS WAS AN OLD POST LMAO - but I will let this post stay unedited since somebody else might find it helpful LOL
PPS: Glad to hear you enjoyed your trip Dan
