If you are building an RV-12 E-LSA, you must strictly follow Van's plans and use Van's E-LSA approved wheel pants option kit (if you so choose to install the optional pants kit). After your E-LSA is signed-off by the FAA/DAR, you can change the pants / add cuffs / add leg fairings / add stabilator end tips / install a kitchen sink as you see fit - provided you remain within the intent of the LSA parameters.
If you are building an RV-12 E-AB, then you can experiment from start to finish and are not strictly bound by Van's plans.