Zip ties are a lifesaver for that kind of mess. I did the same thing under my desk last year after my cat kept batting at the cords. Grabbed a pack of ties and a cheap mount bracket from the hardware store, stuck it to the underside of the desk, and ran everything through it. Took maybe 20 minutes and now you can actually see the floor under there. Just leave a little slack so you can still pull the strip out when you need to. Did you go with the adhesive mounts or screw them in?