There are also books about race car fabrication that will deal with tube frame design at least in one section. I am guessing that the books about building a "Locost 7" (that's a home-built design inspired by the old Lotus 7 car) would give you some basics, at least for that specific design.
This book looks like one of the "Locost" books:
Amazon.com: How to Build a Cheap Sports Car (Motorbooks Workshop): Keith Tanner: Books
-soD