The B class RVs all have the same wheel base. RVs are measured in length from the front bumper to the back bumper. The van nose RVs are from 20' long to 24' (or maybe 28') long. A 20' RV would have been an original maxi van chassis, but the longer RVs were standard van chassis with the extra length added on to the chassis behind where the rear facing doors would have been. The rear overhang behind the rear wheels could have 6' - 8' long, then people hung a tong heavy trailer onto the back end of the extension. See any possible problems with that? Gene