UHaul has had a standing request for any MS owner from the Phoenix, AZ area (or anywhere!) to let them use their car as a template for a new trailer hitch. Will take a few days to complete, but the donee gets a new hitch installed for free. No one has yet done this so UHaul only has a hitch for the Roadster.
The only existing MS hitch is from Eco_Hitch which is well documented here on TMC.
The problem with the Eco_Hitch is that it drops down to the bottom of the bumper where the 90 degree hitch-bar is attached. Thus there is an offset (a 'torque arm') that applies twisting forces to the bumper mount points. This is not specifically what the bumper mount points were designed for; they expect only forward/backward or shear (up/down/sideways) forces which they properly transmit thru the unibody of the car.
But the Eco_Hitch is meant only for light (200 lb max) static loads like a bike rack or a carrying platform so what little torque arm twisting forces they offer to the unibody is minimal. Thus it is authorised by the manufacturer only for these uses and not for pulling trailers.
Any trailer as it is being pulled down the highway will impart pull/push shock forces into the hitch mount points. So the solution with the MS is to move the hitch bar to be perfectly inline with the unibody mounting points where these forces can be distributed without stress. This is easy to do, it just will have the hitch receiver up in the middle of the bumper where you will bang into it with your knee. But so be it, a rubber bumper can be stuffed into the receiver when a trailer is not hooked up.
If the small trailer is no longer level one solution would be to put an offset into the trailer tongue as far from the bumper as possible. This is a lot of work but might be worth it for a sleeper trailer. A drop-down hitch bar is the obvious solution. This will re-introduce some (but not all) of the torque-arm effect of the Eco_Hitch.
For most pulling such as flatbeds (ATV, snow-sleds, cycles, cargo, there is no problem hooking up to the level of the MS bumper center. Also boat trailers and tow bars for flat-towing tiny autos will work fine.
I will be making one up ASAP for a cross country trip and will take notes and measurements before it is buttoned up and pressed into service.
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