Extended Fuel Tanks

By adding weight to the wings without reinforcing the involved structures, you are making use of the reserves built into the Van's original design.
Getting out of a developed spin requires the rudder to overcome the angular momentum of the spinning aircraft. The further a weight is from the center of rotation, the more its weight counts by the square of the distance (see Angular Momentum). For this reason, twin engine airplanes usually have a fin below the tailcone to resist spins. Adding weight to the wings without adding a fin bears the risk of not being able to recover from a developed spin.