If you have a summer bag, like the Marmot summer series, these pack into their small stuff sacks: I pack this at the bottom of the pack, along with clothes & other light-weight stuff. Winter bag I stuff into the bottom of the pack loose: no compression or stuff sack, then load clothes & other light stuff on top of it, pressing it down. You end up with the space at the bottom of the pack completely utilized.

I don't like equipment hanging off the outside of a pack, regardless what it is. If you can't get it into a multi-day pack, then don't bring it.