Keeping your luggage hanging on your shoulder still allows a nimble fingered thief to slide their hand in and see if they can come out with a prize.
This fairly simple addition should help to make that more difficult on any piece of luggage with a zipper around three sides and still allow for the
bag to be completely opened when desired.
A fabric V that is almost the same length as one side of the luggage has half a zipper placed on one side and is sewn to the luggage on the other. The second half of the zipper is sewn onto the luggage itself. This can be done to two separate sides of the luggage if desired.
How this would work: When the V is zipped in place and the luggage zipper at the end of its run the actual luggage zipper has to be moved all the way to the front edge to even slide a hand into the luggage making it more difficult to get into and you a less easy target.
It would still allow you to move the zipper to the front edge to reach down in yourself without much difficulty and when you got to your room all you would need to do would be to unzip the V to fully open the the bag