$4k is a generous and quite a feasible budget.
That’s the crux. If you power up one of those monster laptops without a power supply and do the actual work, the battery will last 50 minutes and the “lap” part will roast the “top” part of your thighs.
hate the keyboards and trackpads and small screens
Does this mean you’re fine lugging 12 pound brick around? Higher end laptops come with mechanical keyboards, quality 18" displays and trackpads have really improved in the recent years.
The questions is: are you looking for a desktop replacement at the travel destination or do you need to Unreal while you travel.
Also, a Windows OS based machine, right?