Fifth Wheel Endgate Restoration

I just bought a truck with a fifth wheel endgate already installed (although I have the original) The endgate is kind of rusted and I want to know if I could get the local shop to spray it with bedliner since I'm getting a bedliner in the truck anyways. I haven't seen anything online with this idea and I'm just wondering why. I can't be the only one thats thought of this. Would it protect to from rust etc.?