I any of you ever going to embark on the project of building the Ferdinand/Elephant with a full interior this WIP thread found on Planet armor can do one of two things to your plans:
1. Either you are utterly deterred from continuing with your plan.
2. Or you got the most detailed description of the Ferdinand interior possible, which should be of good use realizing your plan.
http://www.planetarmor.com/forums/showthread.php?t=4172
Here's an example of the level of detail of the build:
/Tony