Like this with rubber stops made frrom old rear suspension bushes.bending springs sucks.
or you can weld a stop behind the shackle on the hanger to stop it pivoting back to far.
this would be the easyest option and works great.

One per side fitted on the inside. This set is for the MQ which has upper and lower steel bushes.
These won't necessarily stop your efs springs bending as Baja describes. If you have a bit of momentum and hit a bump hard the spring flattens and the shock from the wheels is transmitted through the axle to the leaf which buckles. I think the efs springs are a bit weak here. You could strengthen this weak point by fitting a thicker top leaf or a longer second leaf. I don't think that modifying the front spring hangers will make much difference except that a stop as pictured will reduce the force transmitted through the rear part of the spring.
David