Restrict creation and deletion of customer journeys / smart guides?

Hello Sugar Lovers,

We've setup our client's CRM so that smart guides / customer journeys are created automatically on opportunities and a custom contracts module. So we do not want users to be able to create/delete journeys. 

I can probably prevent deletion via roles, which would suit my needs. But AFAIK roles can't separate create & edit permissions?

In the past, we had hidden the "add journey" button (and template selection) in the widget but that is not very elegant nor actually safe (to put it mildly). That customization broke a few versions back and we did not update it due to other priorities. Now that's back :) 

Any other idea? 

Best regards,
Damien