I flew 3K (backwards facing) and didn't have a worry in the world! The only relevant times are on take-off and landing - the forces are different from what you are used to, but so what? During the 90% that's cruise, when you are in an apartment, you can't really tell the way you face, especially with the window shades down. Have another Champagne and think of ... well, whatever floats your boat
The bed is at 90 degrees to the direction of travel. No forces during cruise, so again, no effect on me lying there.
I've also flown BA reverse herringbone J and it also didn't worry me.