G'day. I'm going to try and put a few pictures up. Don't hold your breath I'm not good with computers.
I have K-Drive saddle bags for touring and though some find the brackets ugly when not using the bags I like to use them as tie down points as well. All my bags are the roll top type, I use them when flying to work and on both bikes. I like that they are fully waterproof and the bag is always tight when adding and taking out clothes by adjusting the amount of rolls to close.
I think the biggest one on the pillion seat is the 40litre from Black Wolf it holds all I need for touring. Tent, exped air mattress, sleeping bag and clothes. Good looking bag with lots of eyelets for securing to bike and other bags to it but it's not wearing as good as the Ortlieb bags. The other two are Ortliebs 21 and 31lt.
The aluminium plate has two plates that clamp it in place. Looking at it now I over did the tie down holes and slots. I only use the four slots on the long edge.