Sounds like there are several plausible solutions. I just wanted to add that in many jurisdictions, collapsible police style batons are as illegal as large knives and guns are. They are considered concealed deadly weapons. I'm not here to judge that being right/wrong, just wanted to pass the info along. A full size frame pump seems like a workable substitute for a last ditch effort against the 1% of dogs the other methods wont work against.