Thanks for the input Peter!
I have tried this now, and there are some quirks:
1. Profiles don't behave the same way as normal email accounts. Eg it's not possible to delete them from the Account dialogue, you have to delete the profile (this will eventually create questions from my clients).
2. It still is hard for a noob (as most of my clients are) to install the profile. Ie, you have to enter the profile dialogue in settings and install the account from there. One dialogue would have been better.
"To install this email account, please enter the password for the email and press OK". That would've been awesome, but I realise that may be hard with all the security stuff involved in iOS and macOS.
3. After test installation on my Mac I had to manually add the "INBOX" prefix in IMAP server settings. That is definitely not that my clients will understand, is there a way to get this done automatically?