Normal force on a 45 degree wall is 45 degrees, In other words it is the force going straight into the wall, not towards the ground. Wearing a bag of rocks won't help because it will just add more force into the ground not normal to the wall. you want normal force not tangential force.
To add more force normal to the surface, you may have to undercling or stem off of something so that the force pushes into the wall.