Originally Posted by
Loren Pechtel
This. A sideways bag should carry a substantial fee even for those who don't otherwise pay for checking a bag.
Yup. Tag the bags in the overhead like the checked bags. You're handed *ONE* tag at check-in, or two if you're in a seat with no underseat storage. Bag is the overhead without a tag? Checked, with a fee.
The tag idea would work quite well.