We did a five month trip from PA. to AK. and back this spring and summer. We typically stay in RV parks as the wife is quite disabled, and not really able to do much boondocking. In all that time, in several dozen parks, I was asked to list the age of our RV maybe two or three times. Typically by a bored clerk who couldn't give a rat's butt hair what we were camping in. To them it was just another line in the paperwork the management requires. There are some places, a very small minority, with a fairly firm rule and they typically come with a price tag to match. Heck, there are even places that only accept Class A "motorcoaches" and requires them to be at least a certain length. That said, if your rig looks half decent, the "ten year rule" gets a lot more play online, than it does in the real world.
The comment about the locals not even knowing about a free public dumpsite gave me a chuckle. I was at a state park in WA. that didn't have a working dump station. The ranger advised that there was definitely one in a small park, in the closest town. I got to the edge of the park, and started a friendly conversation with two older guys who lived in the neighborhood. Neither had a clue about the dump station. A quick search revealed that it was located at the curb, directly across the street from one guy's house. LOL, the guy lived at a dump station and didn't have a clue.