As I said earlier, I can probably fit the two smaller bags into one big duffel that would meet the airline requirements.

I also asked the tour operator and he put it best:

The weight and bag requirements are going to be strictly enforced
from what we were told. No deviations. If I were you I would comply with
their requirements to the letter. If not you risk some bureaucratic
decision from the airline that you could regret. Since I have not been on
Aerolineas since March 2020 I cannot vouch for what they will actually do.

and

What I should have said is that Aerolineas is not a good airline. If there
was another choice I would take it but the pandemic drove the others
basically out of business. The people I encountered did not speak English
well and were basically drones with no independent thought to help out a
customer with alternate bag arrangements. That is why I recommend keeping
to their narrow baggage requirements. Sorry, but that was my experience
with them.