I was cutting a new lamp display panel using a plunge router. The display holes are fine. For the lamp holes, I used a 1/2" straight bit with my plunge router. No matter how lightly I pressed, it did not cleanly cut the final ply and pushed through and splintered the back side so I have a lot of holes with large gashes around them. Not a great big deal for this panel as it is the back side, behind a backglass so nobody will see it unless during maintenance. However, I would like to prevent this for any future builds. For you woodworker experts here, what is the best way to do this right and make a nice clean hole all the way through?

Will do. Thank you.
Did not pre-drill.