In Virginia, perhaps everywhere, if you are using the vehicle for your own personal purposes, such as recreation, you don't need a CDL.
Commercial driver’s license requirements don’t apply to:
operators of emergency vehicles, such as firefighters
active duty military personnel operating military vehicles
operators of farm vehicles when
used by farmers
used to move farm goods, supplies or machinery
to or from their farm
not used as a common or contract motor carrier,
used within 150 miles of the farm
vehicles operated by persons only for personal use,
such as recreational vehicles and rental moving vans.
from page 3 of http://www.dmv.state.va.us/webdoc/pdf/dmv60.pdf
, retrieved 5/23/16 and confirmed with DMV by phone.
When (OK, 'if') I get my bus, I plan to neatly letter just under the driver's window, "Private recreational vehicle - not for hire".
But one has air brakes and goes to Canada, one better have the proper endorsement.