How best to arrange cables in this room...

Every gas fireplace I have come across is basically a small, steel firebox with a 6"-8" exhaust pipe that gets routed outside the home, surrounded by wood framing and drywall, creating a huge "shell" enclosing a lot of wasted space inside.  You can have any local A/V or Custom Integration company fish the speaker cabling through the giant, hollow framed box to the other side with minimal effort and with no issues to the speaker cabling.  

@paradisecom good point. I didn't even think about A/V install companies to do it for some reason. I'll see how it plays out. I may be able to sacrifice use of the fireplace and just put the rack in front of it (im in Texas after all, how many times a year is it going to be relevant to use a fireplace), but have some convincing to do.

The price of 22'+ speaker wires would be a healthy chunk of change, and having to deal with probably 12' extra wire on one side would be a little annoying, but there's options.

If it was me, I would move my listening chair to near the fireplace!

On the uneven cables, my bedroom system’s speaker cables are unequal by about 6’ and I hear no effects. 

@tmiddle the listening position will be about 6ft back from the center of the fireplace.

The price of 22'+ speaker wires would be a healthy chunk of change, and having to deal with probably 12' extra wire on one side would be a little annoying, but there's options.

@mmcgill829 , 25 ft SVS Soundpath ultra speaker cables should run you a bit under 200 $/ pair. It tends to have a thicker meatier sound and looks decent. Don't bash it a priori because it is "affordable" by audiogon standards, i.e., try it before you bash it. I use it for long run surround channels and have also tried it back to back for mains against AQ cables that cost more than some rigs. I seem to prefer the SVS cable with some mix of components.