Look at the older Lenovo workstation laptops for an example of something similar. I have a P50 -- a 3840x2160 15" screen, 32GB of RAM, Xeon E3-1505M v5 @ 2.8GH

Look at the older Lenovo workstation laptops for an example of something similar. I have a P50 -- a 3840x2160 15" screen, 32GB of RAM, Xeon E3-1505M v5 @ 2.8GHz, and a removable battery. It also comes with space (easily accessible!) for extra drives, ram slots, etc. Even with the overkill Xeon CPU, I still get ~5hours of battery life on windows under moderate load. Most importantly, the service manual is a thing of beauty, and has detailed instructions for almost any replacement. This is a laptop designed to be used, upgraded, and used again.