I liked this Home Depot foam buck shaping process. Especially the rear section buildup. Trial fit of rear light assemblies could be done at this point. Equally spaced out mdf sections guide the cutting & shaping process. There are a lot more helpful techniques & details of the entire foam buck construction. A boat tail is a simpler process compared to their complicated design.
http://www.youtube.com/user/BaileyBl...25/xdsFLRmEtpI