I was gonna say what Mac said, and credit him, but instead I just waited for him to post.
But similarly, if the bundle(s) come in from a wall, they can go into a flush-mount low voltage enclosure. There, the cables can be patched if needed, and then continue through the LV enclosure, out of the bottom knockouts, and then out through a few pass-throughs mounted below the enclosure. Leave room for 2-3 more pass-throughs below the enclosure, for the future. Just cut them in later.
Like with Mac's approach, service loops can be stored/hidden in the enclosure.
All that is visible are the bundles coming out of the drywall below the enclosure, which is hidden by the rack.
I wouldn't patch audio cables, though - can pass through the enclosure, out the bottom knockouts, through the drywall pass-through(s), and then into the rack.
I think the Middle Atlantic wire tray is the ideal solution to convey cable bundles from the wall to the rack, but it's not idea for a rack on wheels - best for tracks.
[Link: middleatlantic.com]The cable bundles can be hung from a retractor (tool balancer/spring balancer) or bungee cord, mounted near the top of the rack, in the back.
[Link: avsforum.com][Link: remotecentral.com]