We called one of the larger hospitals in Oshkosh (about an hour from where we were staying) and were told to bring Samantha in and they would try to figure something out at that time.

Fortunately, they did offer the name of a neo-natal center another 10 miles further down the highway.  We called the neo-natal center and were lucky to discover that they had a replacement G-tube 'in-stock' as well as a doctor that was experienced in the insertion process.

So, about three hours later we had the tube replaced and were back home without serious incident.  It is probably a good idea when traveling, to carry as many replacement aparati as possible just for such an emergency.