I just put the finishing touches on my jockey box.
Before I put the SS coils showed up, I had a BBQ cookoff to go to. We got a keg of Shiner (don't have any homebrewed stuff yet). We kept the keg on ice and just used ~20ft of 3/16" beer line (plastic) in the jockey box and kept it covered in ice. It worked great. I didn't get any real cooking effect from the beer line, but it didn't foam since I kept the keg cold.
So short answer is yes, 25ft will work as long as you keep the keg cold.
On a side note, I didn't want to pay big bucks for the coils either, so I bought 304 SS tubing at Grainer (~$50) and bent it myself - saved quite a bit of cash!