??
I am 6' 4" and (barely) fit on the downstairs when the seats are folded down and mattress is placed on top and can stretch completely. I sleep poorly in airline seats, OK in Amtrak seats and better on an Amtrak roomette on the bottom level. If I have multiple days of train travel I will sometimes splurge for a roomette. For example in 2023 I started with Amtrak from Austin to Chicago (roomette) and Chicago to WashingtonDC (seat). I finished with Amtrak from Seattle to Chicago (roomette) and Chicago to Austin (seat). A single night in an Amtrak seat is fine but two or three not as much.