every park is different. need to research where you want to go. my nearby national park (mt rainier) has a 27’ trailer limit for two of its major campgrounds and an 18’ limit for another. in doing my research i found 27’ would get me into 95% of the places I want to go, so that’s what I bought. i just took my TT to Mt rainier this weekend and 27’ fit well, snugly, but not tightly. in general i think the limits are accurate and would plan to adhere to them. obviously, the shorter the better, but we needed a bunk model and like our floorplan for an outdoor camper (it doesn’t have a sofa and wouldn’t be great as a full time trailer or extended indoor living in the snow, humidity, or rain). anything smaller and we would have had to give something up. plus we were set on a particular brand so we had only so many lengths to choose from.