The one we had on our previous trailer, a 2013 Heartland Trail Runner, was welded on.
You would probably need to put another rear bumper back on the trailer, so I doubt you would save much weight.
Maybe mounting your spare tire on the tongue would be a better option for switching out weight from the back to the front.
As for weight . . . we found that the best way to organize weight is to go through the krap we have in the trailer every few months and take out stuff we don't use.
You won't believe how much stuff accumulates in these things.