On my Iron & Resin Terrain pannier, it does not have any support bracket, just straps that go around frame on the Bonneville. The inboard side of bag has a stiffner inside. It does rest against the spring coil. It has been on my bike for five yrs and has suffered zero problems from the coil movement. The Viking bags look to be similar setup and should not need a support rail/rack on Commando.I googled the bags and found https://www.vikingbags.com/viking-bonafide-large-black-motorcycle-cafe-racer-saddlebags/ is the cheapest but I think it will be touching my back shocks so I guess I have to use some bracket to avoid that? Is there any brackets available for this or i just have to get it from the hardware store?
They are Triumph Nylon Panniers, part number A9518150, they are high price full retail you need to find discounted which is not hard.do you have the link for this one?