It is illegal to park in front of the dumpsters marked no parking. However, becasue the signs appear on private property, it is up to the store owner to govern private no-parking signs.
Now our question speaks to who is at fault if you are parked in a no-parking zone.
Arkansas is the last chance state. What this means is, the person who had the last chance to prevent the accident, when all other things are equal, is the one held at fault for insurance purposes. The exception is is one person was not supposed to be driving at all.
In your case, you were not supposed to be parked there. If you had not parked there, in the no-parking spot, the accident would not have happened, so you can be held at fault.
Now that you are goint to court, the court will ask some version of the followinq question: "would the accident have happened anyway?" This means that they will look a the other drive and you form the perspective of:
1. Due diligence of driving: looking both ways, clearing the rear, using mirrors, etc.
2. Speed of the vehicles: was your car sitting still and the other one moving, or were both moving.
3. Where did the car get hit by the other: front quarter panel, rear quarter panel, etc.
I cannot say for sure who was at fault. There are way to many questions. You can be held accountable, but then if the other person was careless, the accident could have happened anyway, he could be at fault.
IN my opion, he or she did not clear the rear, or they would not have backed into you. Despite your illegal parking, I think the other person should be at fault.