I imagine that the guides wil take care of checking all of our luggage as a group so weight and pieces per person probably won't be an issue. If they are checking in 22 people then it seems unlikely that the check in agent will be counting the number of bags. We have been on some group trips where some individuals were obviously overweight while others were traveling lighter and there wasn't an issue about it. I have never had anyone actually weigh a carry on bag. if the size is OK to carry on I wouldn't stress about whether it weighs more than 17 pounds.