Are you certain the lean was not always there? Some motor home manufactures install spacers on the lower/heavier corner to compensate for a naturally imbalanced load, commonly caused with multiple slide outs all placed on one side of the rig. But even slideless rigs can have a lean. Being a former rental, maybe that was just not a priority when the rig was being made.
Maybe your springs are fine. Maybe you need spacers and heavy duty front and rear stabilizer bars. New springs might yield the same lean.
