For travel/delivery we cover both back and front. Once delivered we tell the customer to treat the image with care. The front requires protection whilst in a normal environment the back isn't touched for years on end.
We leave it open and tell them that if they "ding" it on a hard corner of another object, just spray water on the back where the dint shows and iron with a hot iron until dry. This almost always works if the fabric has not been broken.