Have an "apartment" with the nomads, but can't sleep in the bed that's right there in my tent

[Id]

make it make sense or it's just foreshadowing that you were never really apart of the family

[Rickymicky]

it seems to be bugged.
So, before the DLC dropped, when 3 - 5 in-game days pass, if you go and talk to Panam in the trailer with the Ripperdoc, you'd find her standing up (instead of the usual sitting down on her phone). So when you walk up to her, you get the option to hug her, and once you do that, you'll be able to sleep in the bed (and wake up to a special surprise).
I say it's bugged, because ever since PL (Phantom Liberty) dropped and I unlocked the new ending, I haven't been able to do that again lol
But, to respond to your post, yes you CAN sleep in the bed in your tent -- it's definitely possible.

[tx093]

To date, I haven’t seen her standing in the trailer, I’ve almost given up on” moving in with her , like she invited lol.

[Nar!]

I think there's a mod for that. Yeah I was also confused as to why I couldn't rest there. I can use the mirror and the shower that's located outside another trailer, but never the bed (except for the one scene described above).