The label on the hitch does not change the chassis GCWR.
To really know what's what, towing wise, I think you need to know the following:
Gross Vehicle Weight Rating GVWR of the Chassis. If Coach and Chassis have labels (one from Ford another from Winnie, Thor) they should have the same ratings.
Gross Combined Weight Rating CCWR of the Chassis.
GCWR minus GVWR should be what you can tow.
But that's only if the FRAME wasn't stretched OR was stretched to Ford's specs.
To really know what you can do, Coach should be Weighed on a Truck Scale.
Now my opinions:
If it's rear wheel drive with single wheels it may make a suitable RUV. The numbers we've seen so far make it doubtful the RUV's on RAM Promaster are actually suitable. They're front heavy with the FWD, then the frame is extended only behind the axle and that over- (or nearly-) loads the rear axle.
If you weigh the unloaded RUV and don't have at least 1,000 pounds between that weight and GVWR, you won't be happy. Even if you travel as a couple, I'm going to guess 400 for the pair clothed and out the door. Leaves 600 for bedding, clothing, campsite gear, food supplies, etc. You'll need most of that if you're going out for weeks at a time.
Then satisfy yourself that that GCWR - GVWR capacity will tow the vehicle you want to bring along. And please, THINK LIGHT. I don't personally care for Smarts, but they're light. Toyota/Scion, Nissan, Honda, Chevrolet, Ford, all have light "commuter" cars, mostly manual shift to tow four down.
If God's Your Co-Pilot Move Over, jd
2003 Jayco Escapade 31A on 2002 Ford E450 V10 4R100 218" WB