I used to have one behind my SUV. I found one on amazon that was 60" wide and 24" deep. Then they sell a bag that was the same size and 24" tall. It was amazing how much it fit and kept everything clean and dry. for both was like $220
The problem is its not secure. If you wanted something secure you need to get a hard sided one but those get pricy.
To keep it from wobbleing I would put a strap to bumper one side.
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