Hot rod magazine has covered everything from ledsled customs to rail dragsters, v-drive boats to factory muscle-cars to street-rods to corvairs and 914's with v-8's shoehorned into the back..... They have promoted the stuffing of oversized v-8's into just about every known front engine/rwd vehicle under the sun. They have promoted the modification of trucks, panels, and even embraced the vans of the seventies. In all their photo-shoots, they put a "Hot Rod" plate on the front of the vehicle, so I guess the term hot rod covers a lot of different styles of cars....
To me, any v-8/rwd vehicle wearing more tire on the rear, slightly lowered in the front, and dual exhaust with a healthy sound is qualified to be generically referred to as a "Hot Rod"!!