Rain-X really does work (on glass ports), though it's not always 100%. I was lucky to find some here in Indonesia - I never could when I still lived in Hong Kong. Other than denatured alcohol, I'm not sure what it really contains, but it's made by Pennzoil-Quaker, and very flammable, so petroleum distillates seems a reasonable guess. After cleaning and drying the dome exterior, apply the rain-x on a small patch of clean cloth using overlapping circular motions. Remove the haze by buffing with another clean piece of cloth.
It's fairly clear that it would NOT be ok to fly with this stuff in your baggage on most airlines. I plan to preplace a bottle on the liveaboard I'm next going on so I won't have to worry about it. But if someone were to ask (just hypothetically of course) what the best way to try to get it past a more cursory inspection, someone might reply with a suggestion to put the yellow plastic Rain-X bottle in a suitably-sized zip loc bag, do the same with several different similarly-sized plastic bottles of sun screen or similar., and then putting all those in another larger plastic ziploc and putting that in a bag with dive gear. But it wouldn't be me who said that, of course.
The important advice I will take responsibility for, however, is that before attempting to shoot over-unders deep in the mangroves, cover your head and neck with the strongest and stickiest DEET you can find, and try to keep it from washing off. And/or wear a hood. I ended up with bites on top of bites all over my head, neck and ears.

Barrel sponge and soft coral under mangroves, Raja Empat

Archer fish under mangroves, Raja Empat
Frogfish