I just went this route. I had picked up the Evo racks from a forum member last fall, and yesterday acquired a barely-used set of the 45L Trax alu-boxes. Installation of racks & boxes was a breeze (for the most part), but now I need to come up with a taillight/turn signal solution, as my rear fender is chopped.
My plan is to add an LED lightbar with stop/tail/turn to the crossbar between the brackets, and wire it & my current lights with deutsch connectors so I can swap between configurations easily.