The bad news: I'm working on figuring out what I'm going to take with me to Ecuador, and particularly how I'm going to carry it. Everything has to be in carryon luggage -- our group only represents numbers of people in the dozens, and we've had multiple problems with checked luggage either disappearing entirely, or not being found until a couple of weeks later, which is just about as bad. The info I was given is that the main carryon bag can be 51" length + width + depth. That's pretty small; I know the last time I flew plenty of people had carryons that were bigger than that. So I asked the travel agent, and she told me that, well, people often get away with carrying oversized bags, but all she can tell me is what the rules are. And the rules she quoted are that the bag can only be 45" length + width + depth. As luggage goes, that's practically a purse. The only good part of the official rule is that the "personal item" can apparently be pretty much anything up to 36".
Because the other constraint on my luggage is that I have to carry all of it myself from the boat to the lodge -- which is a couple of miles -- I'm figuring on getting a backpack. But I need to figure out how small the backpack has to be; 45" would make it about the size of what I carried my books in in high school, and would make it impossible to bring a full-size tripod.
Partly I'm blowing off steam here, but partly I'm looking for practical advice.