path1 wrote:
It depends on who is measuring and measuring what.  Many times campsite will say no trailers over (fill in a number) but when you actually get to the site there is a ton of room because you can back over the end of camping spot until rear tires run out of room.  And at times you can't because of some obstacle (a barrier they put up or trees etc).  And we've seen places that have said say no trailers over so big because of the road getting into the campground.  
Our TT is roughly 35' end to end now since I added the storage box on the back.  We camped in a state park that said the max RV size was 25' and had no issues.  As path1 said, sometimes you can use Google maps to get a satellite view and see the sites.  Many of the sites in this park were short and the roads were kind of tight, but I had no issues and was able to find one of the longer sites, even though it was in the no hookups section.
Fortunately, the Google satellite pic was taken in the winter when the trees were bare so I could see every site.  Just tried it again on a CG this week, and the satellite pic was taken in the summer, so all you see is the ranger office and bunch of trees.....