I did the same thing using the OEM cable mount, same as a F-350 Ford pick up, I used two lengths of standard 2 inch channel and welded flanges to both ends and bolted to the web of the frame, I welded a 3/16 6 inch by 6 inch plate to the center of the channel and mounted the winch to that plate, that is the perfect place to mount the spare tire, I told the dealer when I bought the coach new that I wanted a spare tire and wheel, they tried to talk me out of it, it took 3 weeks for the wheel to show up as its not a standard wheel, good luck with that on the side of the road if your wheel gets damaged, I carry a large star lug wrench and a bottle jack, I have seen too many people stuck on the side of the road waiting for a tire service to show up.
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