Welcome aboard Done Working. I won't be able to change my name to "Done Working Too" for another 10+ years.
Regarding Class A, B, C, they are categorized by the chassis the RV manufacture starts with, not the end result.
Class A starts with a stripped chassis like this.
Class B starts with a cargo van like this.
Class C starts with a cut-away chassis like this.
Keep in-mind that the chassis manufacture offers RV specific option groups which delete the seats, side mirrors, adding electric windows, door locks, a/c, chrome grille work etc, some of many variances compared to a chassis marketed for commercial use.