I’m not sure I understand your reply - if switching a licence between locations is not an option because changes need to be synchronised between the Cores, this would also be the case if you have a licence for each Core; so what’s different?
I have used Roon on a laptop on holiday for a few albums on said laptop. Music whilst I’m away is all I need. I can live without my own library for a week or two.
I expect you could use a back up of the main library to restore to the other location.