Stromberg Carlson CC-255 Trailer Tray, Anybody have one?

Adding that much weight to the TW is going eat some of the trucks payload.
Watch rear tire rating .
I would take another trip to the scales to see how it would affect the front wheel weight transfer.

It's not the easiest place to get to to remove the generator to take it on/off. I would make sure it clears the gas tanks for refilling.
I would never run it in that location, fumes/noise/vibration transferred to the TT frame.
I keep my genny in the trucks bed and lock it down when I run it there .