My current fifth is 35', my old one was 33'. At private campgrounds I tell them 35", at state and national park campgrounds I tell them 30'. Reason being that private campgrounds pack them in like sardines and longer length may be needed. State and National Parks usually use lower allowable lengths. I have more sites available using 30' in those campgrounds and have never had an issue fitting.
2016 Jayco Eagle HT 29.5BHDS (ordered 12/30/15, delivered 3/8/16)
2015 F-350 crew cab, short bed, 6.7L PSD, Pullrite Superglide 3300 hitch