Thanks... would you explain why 4 vs 2.8 ?
You will get a better picture (more detail) from the 4mm lens with no fish eye effect that you can sometimes see with a 2.8mm lens. The night time performance will also be better because you will have a higher concentration of
IR light in a smaller area.
Your front yard is constrained by three walls, no point in going wider than a 4mm lens as you can't see through walls. The back yard the camera is going to mounted high on the outside of the house looking out and down. The increased height will increase the overall area the camera will see.
My 2385 4mm is covering a very similar sized area to either of the two areas you are looking to cover and works very well.