This is a HUGE part of why I am also solo-poly!!
I recently de-escalated with a partner who used to stay the night. My new beau and I have not reached that stage. I wouldn't mind if he stayed- I think it would be lovely- but when they do go home? I sleep so much better alone! But I was never married for 20 years- I don't have that longevity of experience to miss.
Hang in there! I think you are on to something for yourself here and I imagine those new relationships could grow to more sleep-overs as time allows. Thanks for sharing your thoughts!