With some help of good friends (who like free beer) we finally polished off that half barrel of Lite a few weeks ago with pouring out the first half pint of each evening.
Tonight I went back to work on the cooling line issues. I had nonstop problems with the 2000GPH pump. Even though it had intake threads, it would overheat when run non-submersed. And since it was running outside the Keezer, it had issues pumping the coolant in the right direction. It would pump fine from outside straight up the lines and back down into the copper coil, but not in the opposite direction.
After a few hours of research on the laws of fluid mechanics, I discovered that my original 550GPH pond pump that didn't overheat the bucket of coolant had enough lift for the cooling line, I just had failed to properly prime that line (the pump wasn't strong enough to prime it for me!). I got it all working tonight, and will test the temperature tomorrow.
Two new kegs are on order at my local liquor store for pickup later this week. Another 1/4 barrel of Lite and a 1/6 barrel of Sam Adams Octoberfest... just in time for football season!