I was looking at putting both on. My trailer is just a little 24' box, usually just shy of 6k with the standard load. I was looking to increase the rear ride height when pulling with the bags and reduce the body roll with the bar... a buddy of mine has one on his and he seems to like it. But he came from a gas Ch***... sorry, still cough on that.
I found one as an aftermarket, but not got it yet.. addco and hellwig both make them...