Hi Helen,
I don't have your answer on a Carri-Go's wheel base but I can say that they captured my attention when I was shopping around back in 2006/2007. I ruled them out only because they were 3" taller than my garage door could handle.
About your question in regards to what class that Carri-Go is. When any RV manufacture starts with a cut-away chassis that looks like this, it is a class C. The aero-dynamic cap is commonly referred to as a B+ but is still officially a class C. The cut-away chassis is sold by companies like Ford & GM, for applications like motor homes, ambulances work trucks and box trucks. Some are sold with the back wall and some without pending the application.