Especially with a light trailer, you would be putting a lot of weight on the extreme back of the trailer. Besides the issues with voiding the frame warrantee you would be lifting the tongue up a bit. Bumper mounted racks will tear the bumper off. I'd go for roof mounted racks or a front receiver rack. I tried a roof rack but my factory cross bars are curved, so the bikes tilted, and I needed a ladder to get them on. So I bought a front receiver for 200 installed it in less than an hour and use my existing bike rack with it.