I did the heavier springs exactly like tralertrash above did and it raised the trailer 2". A lot more arch in the springs now. My axle weights at the scale were less than yours for my 7,800 lbs GCWR trailer.
I had a broken spring on the interstate once and replaced the springs with 1,750 OEM springs and they were too flat. I'm convinced most of those springs are manufactured to barely meet spec, if that.
You might replace the springs as a first step to see how it goes. Your axle weights were awfully close to 7,000 max anyway at 6,780.
I then bought some darco plastic material at the hardware store and sealed them in place to cover the scuffed wheel well areas above the tires and then screwed them also outside of where the tire would rub if it should happen again.
Been good for 2 years now. Mine is a Lippert frame, too.