Three options, but first a question-- have you done individual wheel position weights? The "low side" heavy? Anything you can move to the other side of the coach. Remember, moving a 200 pound battery bank from one side to the other "transfers" 400 pounds (minus 400 from one side and plus 400 on the other)!
The three options (assuming you have done all you can on weight distribution:
Replace the "weak" spring.
Add a leaf to the "weak" spring.
Add a spacer between axle and leaf spring on the "weak" side.
All three are acceptable. Consult a truck spring shop in your area. That is what they do for a living.
As all have said, shocks on your chassis carry no weight, so are not part of the equation.
Oh, last comment-- make sure that there is not already a spacer on the "high side" causing the lean. I HAVE seen that!