I can't think of anything in the ANO etc that explicitly bans the carrying of Jerry cans of Avgas.
It is done very widely by the floatplane and bush pilots in Canada and Alaska. Often carried in the floats.
The Alaska Bushwheels people advertise a
five gallon collapsible container for 'Liquids'. I don't think there's much doubt about its intended use. That also benefits from not needing venting and can be rolled up after use.
Last time I needed to do it was for flying to North East Canada and I used the polyethylene jugs that motor racers commonly use. They can be secured easily and have a safety vent in the handles.