I have been reading quite a few best laptop for editing posts recently.
Can't help but ask why? I cannot see a point unless between shoot and final delivery there is no access to a workstation other than your laptop.
For all preview and editing tasks proxies work well. If on dsmc2 you have the option to start editing proxies 5 minutes after the last shot and unless in super urgent delivery you would not want to finish an entire project on one small (ish) screen.
Once you have 2 screens an external gpu enclose, laptop, drives, camera, lenses, tripod and lights with you why not carry a full size pc/mac?