This is by far the cleanest install I have found online! I just purchased everything in your links provided to do this with my install.
My plan is to mount the base station up high and then use the other USB plug to power the keypad which will be mounted halfway down the wall, fishing the wire through the open side of the box.
I would love to know how you fabricated your mounting bracket for the base station. Materials used or process for getting it in there like you did would be beyond helpful. 