Lace them together and drape over carrier.
I use the rat trap to hold them in place, had to bend it slightly.
They are so solid that they can just hang against the mudguard stays or carrier frame.
Marwood found them on ebay, type in motorcycle panniers and you should see them listed. Last time I looked some were up in price by 4x +.
In post #2 above my links for them still work.