I had my rack built to spec. Just happened to be talking to a person who had a friend that was retired and love building things. When I went to his garage turned shop, he must have had 100 wooden turned bowls and vases.
Haven't seen you're system but I have an AVR, DAC, BluRay player, PS2, Wii, Power Center & cable box. Could also fit in a medium sized amp or integrated. (looking at adding a Moon i3.3)
See the link to my system.
Tops shelf is 12" high, 2nd is 8" and bottom is 6". To address the heat thing, I have 8x8 cutouts on each of the middle shelves and the back is open. I use a Parasound fan over the AVR with the fan on low. Never had heat problems. The back of the unit is open with maybe a 3 inch border. There are 3" round holes for cabling going across for each shelf and going down. The center separator is also a frame an not solid so I can have cross flow. I have smoked glass on the front. It's all solid pine. I got lucky. This guy worked with me on the specs, hand built it for $750 and delivered it.
I haven't seen anything on the market that really takes into consideration complex wiring configurations and some of the heavier power cables that we may use. Even those that have 'smart' cabling systems.
I think the only way to go is custom for an enclosed system. At the last Toronto Home show, I found at least on furniture manufacturer that will build to spec and something similar to mine would have been about $1500.
It may be worth investigating.