Weight wise, not a big deal as long as the trailer brakes work well, you will be able to pull it. My 02 F150 hauled this trailer full of lumber with well over 10,000 pounds, more like 14,000 pounds without the trailer, it grunted, but it pulled it without any problems what so ever.
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I have also hauled a Cat 272D with it, and that weighs a good 10,000 pounds, as long as it is centered on my trailer, it pulls really well. Is it legal, probably not, is it good for my F150 truck, no. But the trailer is the one holding the weight, my truck just pulls it, and is in control of stopping it. I don’t do this on a regular basis, but I have done it, and at no time did I feel like it was unsafe to do.