My chiller is in the cooler, but my total run outside of the keezer is only about 7'
You can see the build, pump, and the copper loops
here
So far the results are pretty promising. It did a good job of keeping the beer in the lines cold. Of course, nothing is 100% efficient, so I'm not expecting exact keezer temp in my trunk line. However, last weekend I did measure the temp of a few ounces of beer that sat in the trunk line for about 30 minutes, and it was only 1 degree warmer than the keezer! But, my system is still pretty green, and I have more real-world testing to do.
There are a few things I would recommend...
Don't use beer line for the glycol. The walls are very thick and therefore very inefficient at heat transfer. Also, the diameter would severely restrict your flow rate. If your trunk line won't be moving, I would use copper pipe in the trunk. Copper transfers heat far better than vinyl lines, and your cooling system will be more efficient. Unfortunately, I needed my trunk to be flexible so I could slide the keezer out from under the bar for loading/unloading. I used used 7/16" diameter, thin wall vinyl tube because it fits well with the 3/8" copper in my system. For the parts that don't have to move, I did use copper.
For the chiller, a lot of people here use an old corny for the reservoir, with a pond pump for circulation. From what I've read, they have had pretty good results. My system is a little more complicated for 2 reasons. The first is I don't have room in my keezer for a large tank of coolant. The second is because I thought having a smaller volume, actively cooled with a fan and heat exchanger would present more coolant to the cold keezer air. My total volume is about a pitcher full!
Keep us posted on your progress! I'd love to hear real world results from someone else trying this...