Mike, you will need at least a Class III
(5000 lb rating) hitch on the RV. You will also need to check the weight ratings of the RV. The Gross Combined Weight (GCW)
is the loaded weight of the RV + the toad. This must not exceed the Gross Combined Weight Rating (GCWR)
which is on a label near the driver's seat. The GCWR includes toad, motor home, fuel, water, propane, supplies and passengers. These capacities are set by the manufacturer, but still need to be checked at purchase. Any additional equipment or modifications can change these numbers.
Modifying the hitch doesn't change the capacities in the law's eyes, so welding plates to a hitch won't be helpful if the law or insurance is involved.
You'll find folks on here who will give anecdotal testimony as to, "I towed XX thousand miles and never had a problem." to suggest it's OK to modify a hitch or exceed the GCWR, but unless they offer to defend you with an insurance company or court I'd follow the limits listed for the equipment.
A Caravan can be made to tow with a transmission lube pump, but I'd also have a warning light on the dashboard of the RV to monitor it. You could also consider a tow dolly with brakes, eliminating the need for the lube pump and auxillary brakes in the toad.