Generators are great when you've lost electricity at home (that's a fairly good sized generator you've got). But if you're out in the wilderness and there's anyone within earshot of your generator, they will be hating you for ruining their outdoor experience (I know I would). It doesn't matter if your generator is advertised as "whisper quiet" or has "quiet technology"; it is an engine running and sound travels. Please be respectful if there are neighbors around. Most campgrounds have a quiet-time posted (usually around 2200 if I remember right). So if you're buying one to run something all night, please think about it. Why does anyone try to get away from it all, just to have to listen to someone's generator running? Canvas does not block sounds, and if you're in a motor home and can't hear it, it doesn't mean everyone else can't hear it and you're forcing them to listen to it. And those $89 HF generators sound like a chainsaw running. Been there having to listen to it at night against my will (bastards). When I organize runs, I make sure folks know about generator etiquette in not so polite terms so we all understand. Same thing with folks playing music when camping so everyone within miles (it seems) can hear it. Am I the only one with noise issues?
The cargo carrier would be my last choice. It would kill your departure overhang angle, you'd most likely have to move your spare tire elsewhere (it would be in the way of the generator), and I don't know how you would pull your trailer with that cargo carrier there. The rear receiver hitch might be able to handle the downward weight, but on a tray it will be rocking side-to-side if you're driving off pavement, and it may rip the hitch apart (especially if you built the mount up and out to clear the spare tire). If space is a premium, I would recommend one of those smaller (2000 watt-ish sized) more expensive inverter generators that (I can't believe I'm saying this) are advertised as being super quiet and putting it inside your trailer's box. Something like this:
https://www.harborfreight.com/engin...att-super-quiet-inverter-generator-62523.html
Some people put them on sliding trays (like you would put an electric fridge on). Just a thought.