This is impressive. Not sure I want to take it that far with my luggage though. ;-) I found this for just over a 1USD:
If you mount this to the steerer column at the height of the handle of carry on bag and then use two straps it should be pretty secure...
Yeah, you don't want to use that alone, as then the bag will swing. Two straps will help, in fact then the hanger might not be necessary, but can't hurt as a backup so if the straps come loose, it starts to swing before falling off completely. The rubbery padding is there because most folder handleposts are tapered, though a very slow and shallow taper, so that should work.