Use a hole saw to drill more holes. You can also put two holes parallel to each other and use a saw to connect them forming a slot. Either sand them smooth or purchase flexible banding material to clean up the cuts and you can make most of your runs with very little cable bending.

I did this on the "entertainment system" in the family room which is really a curio cabinet that is only 12" deep. Once I found components that fit I cut the holes and routed the cables. With careful planning you'll never be able to see the holes and slots.

Note: Most of my cables are MonoPrice.