Ok so first picture. I circled where the flex is.
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I had the winch drawn down pretty hard with it hooked to the back of the trailer. I don't think it will be an issue unless I actually need full or near full power of the winch. Im.more worried about the fatigue the channel is under constantly flexing. More bracing, like you and other suggested would take care of this.
The problem is I'd like to keep some space open for a box. 80% of the time I have my truck, so I don't really need a box for stuff but it gets towed with other vehicles as well that don't have a loaded tool box. Just want a few odds and ends. So
@singinwoodwackr suggestion of going front is quite Interesting. As it should help and not take up tongue space. Kinda like the second pic.
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And as another said I can always just chain it fast to the hitch with a binder. Which would be quite easy with some chain and binders.