I've sold the bike but still have a pair of semi-rigid suitcase style pannier bags to fit which I've rediscovered in storage and no longer need. They fix with Velcro straps underneath the pillion seat and have loops to secure them to the footrest hangers or the hooks underneath the seat. They're fairly slender but hold a lot, look good and come with integral rain covers and padlocks to secure the contents.
I'm asking for £65. Collection is from central Norfolk or I can arrange courier delivery at a modest additional cost. Take your TDM touring at a fraction of the price of hard luggage and enjoy the summer..