Length restricted rv parks

Black Rock Mountain SP (Georgia)

We have run into it a few/several times but I can't cite who they were right now.
We have stayed at some that should have been restricted, crowding out into the road.
Most are much older parks that still have not updated with hookups on the wrong sides many times. State parks use to be and COE, we have encountered when looking for possible rv parks to visit for fishing etc. All this is subject to, and has possibly changed now.
Canadian parks some are limited, with clear indications they wish those with Mhs to stay in commercial parks. A clear bias against (rich) Americans, with big Mhs aking up spaces that Canadians with smaller units still exists.

Most newer commercial RV parks have at least some sites 40+ will fit. Although they may not always have a site available when you need it. Older RV parks and national/state//city/COE parks it is far more iffy. You can likely always find something. It just may not be where or what you would like.

RV parks, called or advertised as such? Offhand I can't think of many, if any, that I have personally run across. Possibly the Goldrush campground in Dawson City would have to turn away such RVs due to space constraints, but I don't know that for sure and their web site makes no such statement.

Campgrounds and state parks? There it's rather more common. There are at least one or two Vermont state park campgrounds that I cannot use with my 32' motorhome (and that's ignoring those that are hike-in/walk-in only). There are quite a few more where only a small handful of the sites are suitable for larger RVs.