Autodiscover Hybrid Exchange multiple SMTP domains

We have an AD with Exchange 2013 that has SMTP domain @contoso.com.
For this we have a SAN certificate with;

-autodiscover.contoso.com
-mail.contoso.com

So our workers have mail address alias@contoso.com
Setting up hybrid was no problem and works for contoso.com workers.

Now we also want to have cowokers that we would like to give SMTP domain @cowokers.contoso.com and incorporate them in the hybrid Exchange.
Steps would be add the domain to office 365, add the domain to Exchange 2013 Accepted Domains, enable the "Autodiscover Domain feature (audod)" and run the HCW.

Now i know i'm missing a step, autodiscover for client lookups for coworkers (autodiscover.cowokers.contoso.com)
I know the "Autodiscover Domain feature (audod)" is only for hybrid traffic and does nothing for client mail account setup so i need to arrange something but what...

- I know we can use HTTP redirect for autodiscover.cowokers.contoso.com to autodiscover.contoso.com but this gives a popup to Outlook client (also Outlook 2010 client?)
- I know we can use SRV record redirect for autodiscover.cowokers.contoso.com to autodiscover.contoso.com but SRV records are not supported in hybrid Exchange
- Add autodiscover.cowokers.contoso.com to our current certificate but can we have such certificate (autodiscover.contoso.com, mail.contoso.com, autodiscover.cowokers.contoso.com)? And on our current Autodiscover VDIR and client access server we have configured autodiscover.contoso.com as internal and external URL so will this work?

What is best practise in my situation?