I did a gravel pad in back of my house coming off the alley. It's next to my 2 1/2 car garage, and is wide enough to park 2 cars if needed. My TT is only 21' ball to bumper, so it fits easily. I figure I can always do concrete or asphalt later if I want, but the gravel has been sufficient and much cheaper. Word of warning, weeds do grow through/in the gravel, even with a high quality landscape fabric underneath.
As far as codes, I've seen plenty of gravel parking pads in my town, so I didn't bother checking. I know the code admin people actually do drive around looking for violations, and I haven't gotten any grief after a couple years.