experience

I have some experience in shooting while traveling, so that will come in handy when choosing the right gear. Most importantly however, my past experiences allowed me to realize couple of things.

First of all, we do have only one pair of hands, which limits the number of things we can do at once. We can't (well, most of us at least) take good pictures and videos at the same time. Also, even if you have just one camera but lots of accessories for it, chances are you're not going to use all of that (lenses, gimbals, microphones, etc.). Even if you could take all the gear there is on your trip, you won't use it all.

Conclusion: take as little gear as possible, as you probably won't use all of it.

Secondly, when you are traveling for fun and not for work, taking pictures/videos is usually secondary activity, primary being actually enjoying the trip.

Conclusion: take as little gear as possible, so the gear doesn't come in the way of you enjoying your time.

Third: if you take your camera with you, you also have to take some other things with it: camera case, spare batteries, chargers, cables, cards, etc. This means that if you take two cameras, you most likely will have twice as much accessories. One could think: maybe go minimalist and just take an iPhone? That is also an option, however, from my experience that would be somewhat limiting and I think I couldn't take some of my shots with just an iPhone (for various reasons).

Conclusion: take as little gear as possible, but don't go too far (iPhone alone might not be enough).