Brian, You dont have to worry about this plane. It is a snop to build. I had not built a kit in over 10 years when I started this one. As we speak there is a class of 7th and 8th graders building one for a class project. It is not the first kit for many of them but it may be the biggest, and perhaps the most complex. The interior is, eh, spacious? almost 6 inches wide and 10 inches long. When installed a 12 oz tank barely pokes into radio bay. Check ot the photos of my radio box installatin and you will get an idea of its size.
As you start your build you might like to reread the thread and look for my Cautions and Warnings. I made all the mistakes for you and you can learn from my missteps.