I used tie wraps to secure the fender. Works better than it sounds. Make sure you put some velcro (just one side to insulate the vibration) between the fender and the controller or it's going to rattle.
I used a tie wrap and a spacer to secure the fender at the top as well. Seemed like it was always moving around. Securely fastened to the rack, it's rock solid now.
And yes, I used tie wraps and a little double sided tape to secure the controller as well. 2 of them, top and bottom, just for back up in case one did let go.
Mine has a couple of years of riding and quite a few miles on that setup without any sign of trouble. Actually just got back from a short ride!