My question is the following:
How to let users use my wildcard SSL with their custom domain in my multisite network?
In the Domain Mapping plugin page you say it's possible, but some people told me it can't work because they say every.
With these settings complete, your users can go to their admin dashboard > Tools > Domain Mapping and complete the steps to add their own domain and make use of your SSL certificate without installing their own.
As I don't have a wildcard SSL for the moment (I'm waiting for the Let's Encrypt wildcard due in january 2018) I can't test this but this is very very important for me to get a clear answer to this.