Hey @ggoisset i have just asked a question concerning SSO here and now i read your question/concern here … and i think to myself:
wait, maybe Guillaume - in his setting - did find a solution how to SSO while using AD-LDAPS! 
so … if i may ask … did you? Are you using SSO for your users or do they have to manually enter credentials? 
thank you for consideration! 
cheers
Daniel