Will adjusting B&W pivot arms forward help ride?

Moving the weight up a bit may help this problem. Its best to have a hitch 4-6" infront of the rear axle anyway. Another thing I do when towing, not matter what it is, is let off the gas and grab the trailer brakes when going over bumps like that. It really helps keep the bounce down. Its most notable on heavy single axle trailers, but works just the same for a heavy loaded GN, or 5er in this case. See if that helps any.