play a game with him to see how long he can stay in one place...you play along too...the first one who moves, loses. first one who wins gets a prize. keep prizes packed where you can reach them. oohh ya he might be alittle young for that, but you can try.
They also make larger strollers for kids with developmental disabilities...you could get one of those, at least for the trip.
I also like the idea of splitting up the work...that will help alot. You can tag team, so nether one of you get tired out.
In situations like the luggage thingie and security, hold on to him and dont let go until you are done.
of course that might lead to a meltdown...so experiment with that first.
good luck on your trip...although I think you are nuts to undertake this. Cant you get a babysitter for a few weeks?
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All art is a kind of confession, more or less oblique. All artists, if they are to survive, are forced, at last, to tell the whole story; to vomit the anguish up.
-James Baldwin