Following up on my own post :) I looked at same of the local municipality codes. Some of the specifically define truck campers, some of them define them as RV's, and some don't. For example, here is one in which we are not (unless dismounted), Redmond WA regarding parking:
"Recreational and Utility Vehicles. Travel trailers, boats, jet skis, wind surfing boards, folding tent trailers, motor homes, truck campers removed from a truck or pickup, horse trailers, boat trailers with or without boats, and utility trailers. This definition does not include pickup or light trucks, that are10,000 pounds gross weight or less, with or without a mounted camper unit, which are primarily used by the property owner for transportation purposes."
I guess the overall answer to whether or not we are "RV's" is it depends.