I feel your pain, my truck was rearended less than a year old on the same side (driver rear). I was similar damage to your pic, just included the bumper as well. Repair was more like $7k (the BLIS tail light alone is $1300), and I can tell you now, you won't really like how it turns out-to replace the bedside, they cut the welds on the front of the bed and then rivet the new bedside on...so if you look between the cab and bed you will see a vertical string of rivets (like 30 of them) to reattach the bedside to the bed front.
Sorry man!