MLC 45L

I have this and use it for run commuting to the office. It would be way too small for one-bag option for your trip. I have a Patagonia Black Hole MLC 45L which I use for my travel one-bag option which works super well.

Not sure about space but if you do want to be on the safe side, the patagonia black hole MLC (45L) and cotopaxi allpa (42L) seem like solid options with the luggage style opening that I think makes a great travel backpack.

Heya, I have the 45 MLC and a 30 Refugio which is not what you're asking about but I think I have enough experience with both while traveling to give you some idea. The 45L MLC is not a great size in my opinion because of how it's structured. The middle panel just blocks things from being filled, so

if you're looking for a carryon / overhead bag that is bigger than the yeti, but very similar in layout - check out the Black Hole MLC 45L. they also have a Mini MLC at 30L, but it looks like it would be essentially the same as your existing bag.

I have the patagonia black hole MLC 45L and I feel like I can get a lot of stuff in there