Common problem with long (in the dimension of the length of the bicycle) panniers, try a different rack like a Tubus Cosmo/Logo/Cargo that allow you to get the bag quite far away, also Thorn's expedition rack is very long and adaptable. Both have struts from chainstay_brazeons to rack that can be very long. Shown rack is about the worst type of model for helping to avoid sway into the wheel, with just the V support for horizontal surface.