Hello sunseeker -- Welcome to the Forums! Pathfinder? Maybe a 19' Bambi but I surely wouldn't go much larger. The Pathfinder-titled http://www.airforums.com/forums/f463...ccd-38632.html
thread doesn't really address the issue. But Pathfinders are mentioned quite often if you do a general search -- there's a bit of work to pick through the threads.
Excess muscle is always the easy answer to any tow equation. I do feel that a 23-footer is asking too much of a 6 cylinder Pathfinder. Consider that the listed 700# 23' International hitch weight does not reflect the added weight of propane in the tanks or weight distribution gear mounted at the A-frame/bumper. Most of this up front weight is going to add to hitch weight. With a modest amount of personal gear aboard I will almost guarantee a hitch weight of 850# -- probably a bit more.
Nissan's Pathfinder online specs
don't begin to provide useful figures -- a caution. Your manual would have load capacity (also called payload) figures. This is the total amount of weight you can load in or on your Pathfinder and keep it within specs for frame, suspension and running gear -- with safety of emergency braking and maneuvering being my principal interest. For instance Edmunds lists a 1186# payload for a 2007 V6 4WD LE
. That gives you a scarce 300 pounds of added driver/passengers, pets, options, gear onboard the tow vehicle. And this assumes that the listed payload already includes a heavier Class III/IV hitch receiver. A tow package with tow prewire and extra tranny cooling is almost mandatory.
Buying a smaller Airstream than fits your needs could result in an unsatisfactory user experience or buying again in a couple seasons -- resulting in eating out-the-door depreciation twice. For that kind of money I'd say kick the tires on all the Airstreams in sight, plan for what fits your needs, and then go for an adequate tow vehicle. With this path you could economize more than you would by staying shackled to such a limited Pathfinder ... in my opinion.