We do want to share a calendar, but not contacts, as it complicates our individual phones. I have heard that creating separate iCould accounts might help. Is it a 'no-risk' test?
Yep, you both can use your own iCloud id's and share a calendar too.
Simply set up both accounts, go to Calendar app, tap on calendars at the bottom of the screen
Select which calendar you want to share by clicking 'I' in the circle
And finally tap Add Person and fill in the new mail address of the other person who has created his/her new account.