Just tossing this out.
This old posting might help you. Had it booked marked for years now. Someday I'm going to do something with our class C. Don't know what to do with our Trailer without giving up interior room. Different style of RV but might help or you get ideas from. And there is another posting with some of same authors as link below that had charts and more detailed info. You'll have to search them out. All were over 12 months ago. One poster owned a couple patents, and had useful data.
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/17575645/srt/pa/pging/1/page/1