Thing is you don't actually have to use a laptop anymore you can get good wireless keyboard+mouse, plunk your pc next to your bed and use a monitor arm to have the monitor over your bed.
The ergonomics are 1000% better and it removes the thermal issues
you can also use this solution with a laptop, just need a side table to put it on as long as you cable manage the monitor cable properly its a pretty nice setup and no more heat/crappy ergonomics
This obviously depends on how your bed/room is setup but it might be worth looking into
Also new laptops probably have alot more power budget then what you were used to so they will heat you up quite a bit more then before