Oh, those are really neat! There may be room up there for that and my Garmin.
I dug around and found the mounts for my U-lock and installed them on Friday. So far, so good but I am still using the velcro strip to hold it to the rack in one place just in case the mount doesn't hold. I did 32 miles on Saturday and a lot of it was quite bumpy and it didn't seem to move a bit.