Alter two images - replace background & size/scale to match

I have two photos. The sunset photo needs to become the background. I am only interested in the horizon/sky of the sunset to replace the blue sky/horizon of the second photo. On the second photo, I need the two pieces of equipment to be the only objects showing on the sunset image. There are many braces and ladders, and i do not want the blue there. It needs to look as if I took the picture of the two pieces of equipment at sunset instead of during the daylight hours. The wires extending from the rig in the second photo do not need to be there, but if you can, that would be okay as well. I need the images edited so they don't appear to be a fake picture. But, that it was taken at the same time. If there is any quick adjustments that can be made to improve the overall quality and color of the image that would be nice as well. The total image dimensions need to be letter sized paper, it will cover the front of a 8-1/2" x 11" page. Any questions, please let me know. I need this completed ASAP. Thanks