right oh, so I didn't take pictures of what I'm about to describe, because it was an abysmal failure, but let me try and describe it:
I had tried tying on a massive tank bag to the passenger seat, with a tent, sleeping pad and sleeping pad strapped to it. I found the seat to bend upward, and wobble. I tried to fix this by building "wings", which bolted to the sub frame.... They were dangerous and just a bad idea to begin with.... Another factor is also the ninjette's hips, which are quite wide, and although sexy, difficult to deal with when strapping on bags....
What I ended up with, is an idea, yet to be executed, of using 1" wide webbing, with regular snaps you can buy form a camping store, and bolting 2 straps to each side, to be clipped into the soft luggage when it's on the bike. When the luggage is not on the bike, it will just hide underneath the seat/cowl, and the straps will stay bolted to the subframe... You could use this system for hard luggage as well, by simply bolting webbing with the appropriate snaps to the luggage, and then strapping it to the seat...
Why do I think this would be best? Because it's easy to remove the luggage, it's secure (weight wise), it's just not secure, security wise, BUT it also allows one to have a passenger seat, which is nice when traveling...

Once could always add on a cable/chain to add some security....
As I get around to this this winter, I'll be posting up some of it. If somebody beats me to it, cool!