I'm gathering parts for the same project. I have Givi 35's mounted on my 2012 DL650. I'm going to mount a short fishing rod tube and a second tool tube on the bike. The tool tube will be mounted all the time but the rod tube will probably be removable.
I have the tubes and I plan on working on a mounting design during the winter. Plastic zip ties will work but I want something a little more secure and lockable. It's a shame there is a need to lock things but that's the world of today. In days of old the first time stealing cost you a hand, and second time your head. Seems like that might go well in todays world too.
Anyway, I haven't come up with a firm mounting design but I'm leaning toward some type of aluminum bolt on frame. If it works out I'll let you know.