As a workaround in Opera installation folder > installer_prefs you have to change:
"singleprofile":False to "singleprofile":True
It's a .Json file and may be edit with notepad.
Then, it will create a new profile pointing to Data in Opera Installation folder and every link will be opened with it, as a default Profile folder.
This works pretty nicely. Do you know if it will stay set that way when Opera updates itself?
Yes, it will be since it's the same parameters for Opera USB installation, just keep your mod shortcuts save and keep in mind, if u use a default Opera shorcut it will create/use a profile inside Opera Installation.
Thanks @leocg, It worked for me !!!
For those who got the same question like me, create a shortcut to the "launcher.exe" in Opera installed folder, rightclick on it and select Property, at "Target", add those command :
--user-data-dir=<YourCustomDirectory> -> change the Profile folder
--disk-cache-dir=<YourCustomDirectory> -> change the Cache folder
