Where can you buy some door sill protector plates for the rear (Super Crew) like come factory on the front doors? Need something in these large unprotected areas.

 

You should to find out the part numbers for the front ones and then buy them and trim them to fit the rear doors. I remember the old 04 guys doing that.

I sometimes get questions about the Autoventshade (AVS) door sill protectors that I have on my truck (there's a photo of them in my album), but I guess that AVS doesn't make them anymore. I had bought the 4-piece set for my 04 truck, only used the rears on that, and then saved the fronts and trimmed them to fit my new 09.