Richard, I always read this forum with plans to upgrade to a Newell.
I have been towing a Class B - Forest River MB Cruiser (Sprinter Chassis) behind a Beaver Patriot Thunder for many years.
The Beaver has a 425 hp C-12 Cat engine. The Sprinter weighs in at 7,100 lbs. I use a Roadmaster base plate, Roadmaster Blackhawk 2 - 10,000 lb tow bar (stays on the Beaver) and a Remco driveshaft disconnect. The trick with towing this much weight it to install the Air Force One brake system on the Sprinter. With the AFO you always have power brakes on the sprinter when the engine is off. Do not use a braking system that pushes on the brake petal when it is dead. (no vacuum in the booster)
Join us on this forum
http://sprinter-source.com/forum/
Mike Stephenson
Lubbock, TX