I assume the bumper has already been scraping, so whether it can hold the weight is kind of irrelevant?
I'd start with the factory lift kit though, and see where you are.
I'm thinking of installing the lift kit myself. My unlifted 17B didn't do well off-road last July 4th. I bent up and destroyed the electric lift jack. It hangs down too low. I replaced it with a manual crank one that does not drop down below the rails at all now. A 2" lift would help the trailer survive my ambitious camping spot choices.
I wonder if the rear bumper could take the weight of the trailer in this instance. Does anyone know?
In another thread there was discussion about how ETI discontinued using scissor jacks for stabilizers because they were capable of lifting corners of the trailer off the ground, potentially deforming the frame.