This is an easy problem to remedy. Buy or borrow three or four of those giant coolers that you use for deep-sea fishing. Igloo makes a 162-quart marine cooler that fits the bill nicely. Load your wine up (stand 'em up so you can control the water/ice level), ice 'em down, and hit the road.
When your ice starts to turn to water, stop at a truck stop, drain the coolers, re-ice 'em down, and re-hit the road. I'd guess you'd only have to re-load with ice once or twice.
When you get back to Plano, drain the coolers and take your babies into the cellar. That way, they're only going from 32 degrees to 55 degrees. I wouldn't think that this would be a temperature fluctauation that would shock the wine (assuming you won't be drinking them for a week or two).
Kind of a low-tech and redneck solution, but that's how I'd do it, especially if I was driving ayway.
"Well, the world needs ditch-diggers too."