Hi Robert
We towed with a dolly and it is a BIG pain in the b*tt to say the least.
On the info you've provided it looks like you'd be close to maxxed out for your hitch and that's not a good idea. I think in the long run you will be happier not having to mess with a dolly and example would be if you had to unhook in a gas station or some other tight spot. That would mean unloading the car off the dolly, getting the dolly hooked to the car , moving the car with dolly and moving the motorhome then rehooking and reloading all.
We found loading the car on the dolly a rather exciting experience when it was wet since the car tires and the dolly pads were slippery. More thrills than we wanted

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Travel safe whatever your choice is.