Many, but not all, dealerships will either have a "campground" on site or an arrangement with a nearby one so that you get one free night to try everything. Depending on what price you are paying, and whether you are buying new or used, you may be able to get your instructions and an inspection (with you present), then spend a night it it so you can make a list of questions and things that don't work right, then the next day they fix and reinstruct, and you repeat the process until you are happy. Don't expect that for a 10-year-old popup, but a brand-new Airstream should get the royal treatment.
Mercury Mountaineer towing mpg 181(both sold)
1993 Foretravel U300 40'