I think this might look like
access = yes
access:conditional = no @ 00:00-dawn, dusk-24:00

Thoughts?  I will probably revisit this later.

https://help.openstreetmap.org/questions/35189/appropriate-to-use-opening_hours-on-a-road-gate-or-trail

https://wiki.openstreetmap.org/wiki/Key:opening_hours/specification